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2017-07-21Merge branch 'sched-urgent-for-linus' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull scheduler fixes from Ingo Molnar: "A cputime fix and code comments/organization fix to the deadline scheduler" * 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: sched/deadline: Fix confusing comments about selection of top pi-waiter sched/cputime: Don't use smp_processor_id() in preemptible context
2017-07-14Merge branches 'pm-cpufreq-sched' and 'intel_pstate'Rafael J. Wysocki
* pm-cpufreq-sched: cpufreq: schedutil: Fix sugov_start() versus sugov_update_shared() race * intel_pstate: cpufreq: intel_pstate: Fix ratio setting for min_perf_pct
2017-07-14sched/deadline: Fix confusing comments about selection of top pi-waiterJoel Fernandes
This comment in the code is incomplete, and I believe it begs a definition of dl_boosted to make sense of the condition that follows. Rewrite the comment and also rearrange the condition that follows to reflect the first condition "we have a top pi-waiter which is a SCHED_DEADLINE task" in that order. Also fix a typo that follows. Signed-off-by: Joel Fernandes <joelaf@google.com> Reviewed-by: Daniel Bristot de Oliveira <bristot@redhat.com> Acked-by: Juri Lelli <juri.lelli@arm.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/20170713022429.10307-1-joelaf@google.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-07-14sched/cputime: Don't use smp_processor_id() in preemptible contextWanpeng Li
Recent kernels trigger this warning: BUG: using smp_processor_id() in preemptible [00000000] code: 99-trinity/181 caller is debug_smp_processor_id+0x17/0x19 CPU: 0 PID: 181 Comm: 99-trinity Not tainted 4.12.0-01059-g2a42eb9 #1 Call Trace: dump_stack+0x82/0xb8 check_preemption_disabled() debug_smp_processor_id() vtime_delta() task_cputime() thread_group_cputime() thread_group_cputime_adjusted() wait_consider_task() do_wait() SYSC_wait4() do_syscall_64() entry_SYSCALL64_slow_path() As Frederic pointed out: | Although those sched_clock_cpu() things seem to only matter when the | sched_clock() is unstable. And that stability is a condition for nohz_full | to work anyway. So probably sched_clock() alone would be enough. This patch fixes it by replacing sched_clock_cpu() with sched_clock() to avoid calling smp_processor_id() in a preemptible context. Reported-by: Xiaolong Ye <xiaolong.ye@intel.com> Signed-off-by: Wanpeng Li <wanpeng.li@hotmail.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Luiz Capitulino <lcapitulino@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rik van Riel <riel@redhat.com> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/1499586028-7402-1-git-send-email-wanpeng.li@hotmail.com [ Prettified the changelog. ] Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-07-12cpufreq: schedutil: Fix sugov_start() versus sugov_update_shared() raceVikram Mulukutla
With a shared policy in place, when one of the CPUs in the policy is hotplugged out and then brought back online, sugov_stop() and sugov_start() are called in order. sugov_stop() removes utilization hooks for each CPU in the policy and does nothing else in the for_each_cpu() loop. sugov_start() on the other hand iterates through the CPUs in the policy and re-initializes the per-cpu structure _and_ adds the utilization hook. This implies that the scheduler is allowed to invoke a CPU's utilization update hook when the rest of the per-cpu structures have yet to be re-inited. Apart from some strange values in tracepoints this doesn't cause a problem, but if we do end up accessing a pointer from the per-cpu sugov_cpu structure somewhere in the sugov_update_shared() path, we will likely see crashes since the memset for another CPU in the policy is free to race with sugov_update_shared from the CPU that is ready to go. So let's fix this now to first init all per-cpu structures, and then add the per-cpu utilization update hooks all at once. Signed-off-by: Vikram Mulukutla <markivx@codeaurora.org> Acked-by: Viresh Kumar <viresh.kumar@linaro.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2017-07-05sched/fair: Fix load_balance() affinity redo pathJeffrey Hugo
If load_balance() fails to migrate any tasks because all tasks were affined, load_balance() removes the source CPU from consideration and attempts to redo and balance among the new subset of CPUs. There is a bug in this code path where the algorithm considers all active CPUs in the system (minus the source that was just masked out). This is not valid for two reasons: some active CPUs may not be in the current scheduling domain and one of the active CPUs is dst_cpu. These CPUs should not be considered, as we cannot pull load from them. Instead of failing out of load_balance(), we may end up redoing the search with no valid CPUs and incorrectly concluding the domain is balanced. Additionally, if the group_imbalance flag was just set, it may also be incorrectly unset, thus the flag will not be seen by other CPUs in future load_balance() runs as that algorithm intends. Fix the check by removing CPUs not in the current domain and the dst_cpu from considertation, thus limiting the evaluation to valid remaining CPUs from which load might be migrated. Co-authored-by: Austin Christ <austinwc@codeaurora.org> Co-authored-by: Dietmar Eggemann <dietmar.eggemann@arm.com> Tested-by: Tyler Baicar <tbaicar@codeaurora.org> Signed-off-by: Jeffrey Hugo <jhugo@codeaurora.org> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Austin Christ <austinwc@codeaurora.org> Cc: Dietmar Eggemann <dietmar.eggemann@arm.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Timur Tabi <timur@codeaurora.org> Link: http://lkml.kernel.org/r/1496863138-11322-2-git-send-email-jhugo@codeaurora.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-07-05sched/cputime: Accumulate vtime on top of nsec clocksourceWanpeng Li
Currently the cputime source used by vtime is jiffies. When we cross a context boundary and jiffies have changed since the last snapshot, the pending cputime is accounted to the switching out context. This system works ok if the ticks are not aligned across CPUs. If they instead are aligned (ie: all fire at the same time) and the CPUs run in userspace, the jiffies change is only observed on tick exit and therefore the user cputime is accounted as system cputime. This is because the CPU that maintains timekeeping fires its tick at the same time as the others. It updates jiffies in the middle of the tick and the other CPUs see that update on IRQ exit: CPU 0 (timekeeper) CPU 1 ------------------- ------------- jiffies = N ... run in userspace for a jiffy tick entry tick entry (sees jiffies = N) set jiffies = N + 1 tick exit tick exit (sees jiffies = N + 1) account 1 jiffy as stime Fix this with using a nanosec clock source instead of jiffies. The cputime is then accumulated and flushed everytime the pending delta reaches a jiffy in order to mitigate the accounting overhead. [ fweisbec: changelog, rebase on struct vtime, field renames, add delta on cputime readers, keep idle vtime as-is (low overhead accounting), harmonize clock sources. ] Suggested-by: Thomas Gleixner <tglx@linutronix.de> Reported-by: Luiz Capitulino <lcapitulino@redhat.com> Tested-by: Luiz Capitulino <lcapitulino@redhat.com> Signed-off-by: Wanpeng Li <wanpeng.li@hotmail.com> Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Rik van Riel <riel@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Wanpeng Li <kernellwp@gmail.com> Link: http://lkml.kernel.org/r/1498756511-11714-6-git-send-email-fweisbec@gmail.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-07-05sched/cputime: Move the vtime task fields to their own structFrederic Weisbecker
We are about to add vtime accumulation fields to the task struct. Let's avoid more bloatification and gather vtime information to their own struct. Tested-by: Luiz Capitulino <lcapitulino@redhat.com> Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Rik van Riel <riel@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Wanpeng Li <kernellwp@gmail.com> Link: http://lkml.kernel.org/r/1498756511-11714-5-git-send-email-fweisbec@gmail.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-07-05sched/cputime: Rename vtime fieldsFrederic Weisbecker
The current "snapshot" based naming on vtime fields suggests we record some past event but that's a low level picture of their actual purpose which comes out blurry. The real point of these fields is to run a basic state machine that tracks down cputime entry while switching between contexts. So lets reflect that with more meaningful names. Tested-by: Luiz Capitulino <lcapitulino@redhat.com> Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Rik van Riel <riel@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Wanpeng Li <kernellwp@gmail.com> Link: http://lkml.kernel.org/r/1498756511-11714-4-git-send-email-fweisbec@gmail.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-07-05sched/cputime: Always set tsk->vtime_snap_whence after accounting vtimeFrederic Weisbecker
Even though it doesn't have functional consequences, setting the task's new context state after we actually accounted the pending vtime from the old context state makes more sense from a review perspective. vtime_user_exit() is the only function that doesn't follow that rule and that can bug the reviewer for a little while until he realizes there is no reason for this special case. Tested-by: Luiz Capitulino <lcapitulino@redhat.com> Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Rik van Riel <riel@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Wanpeng Li <kernellwp@gmail.com> Link: http://lkml.kernel.org/r/1498756511-11714-3-git-send-email-fweisbec@gmail.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-07-05vtime, sched/cputime: Remove vtime_account_user()Frederic Weisbecker
It's an unnecessary function between vtime_user_exit() and account_user_time(). Tested-by: Luiz Capitulino <lcapitulino@redhat.com> Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Rik van Riel <riel@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Wanpeng Li <kernellwp@gmail.com> Link: http://lkml.kernel.org/r/1498756511-11714-2-git-send-email-fweisbec@gmail.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-07-04Revert "sched/cputime: Refactor the cputime_adjust() code"Ingo Molnar
This reverts commit 72298e5c92c50edd8cb7cfda4519483ce65fa166. As Peter explains: > Argh, no... That code was perfectly fine. The new code otoh is > convoluted. > > The old code had the following form: > > if (exception1) > deal with exception1 > > if (execption2) > deal with exception2 > > do normal stuff > > Which is as simple and straight forward as it gets. > > The new code otoh reads like: > > if (!exception1) { > if (exception2) > deal with exception 2 > else > do normal stuff > } So restore the old form. Also fix the comment describing the logic, as it was confusing. Requested-by: Peter Zijlstra <peterz@infradead.org> Cc: Gustavo A. R. Silva <garsilva@embeddedor.com> Cc: Frans Klaver <fransklaver@gmail.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Rik van Riel <riel@redhat.com> Cc: Stanislaw Gruszka <sgruszka@redhat.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Wanpeng Li <wanpeng.li@hotmail.com> Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-07-03Merge branch 'sched-core-for-linus' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull scheduler updates from Ingo Molnar: "The main changes in this cycle were: - Add the SYSTEM_SCHEDULING bootup state to move various scheduler debug checks earlier into the bootup. This turns silent and sporadically deadly bugs into nice, deterministic splats. Fix some of the splats that triggered. (Thomas Gleixner) - A round of restructuring and refactoring of the load-balancing and topology code (Peter Zijlstra) - Another round of consolidating ~20 of incremental scheduler code history: this time in terms of wait-queue nomenclature. (I didn't get much feedback on these renaming patches, and we can still easily change any names I might have misplaced, so if anyone hates a new name, please holler and I'll fix it.) (Ingo Molnar) - sched/numa improvements, fixes and updates (Rik van Riel) - Another round of x86/tsc scheduler clock code improvements, in hope of making it more robust (Peter Zijlstra) - Improve NOHZ behavior (Frederic Weisbecker) - Deadline scheduler improvements and fixes (Luca Abeni, Daniel Bristot de Oliveira) - Simplify and optimize the topology setup code (Lauro Ramos Venancio) - Debloat and decouple scheduler code some more (Nicolas Pitre) - Simplify code by making better use of llist primitives (Byungchul Park) - ... plus other fixes and improvements" * 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (103 commits) sched/cputime: Refactor the cputime_adjust() code sched/debug: Expose the number of RT/DL tasks that can migrate sched/numa: Hide numa_wake_affine() from UP build sched/fair: Remove effective_load() sched/numa: Implement NUMA node level wake_affine() sched/fair: Simplify wake_affine() for the single socket case sched/numa: Override part of migrate_degrades_locality() when idle balancing sched/rt: Move RT related code from sched/core.c to sched/rt.c sched/deadline: Move DL related code from sched/core.c to sched/deadline.c sched/cpuset: Only offer CONFIG_CPUSETS if SMP is enabled sched/fair: Spare idle load balancing on nohz_full CPUs nohz: Move idle balancer registration to the idle path sched/loadavg: Generalize "_idle" naming to "_nohz" sched/core: Drop the unused try_get_task_struct() helper function sched/fair: WARN() and refuse to set buddy when !se->on_rq sched/debug: Fix SCHED_WARN_ON() to return a value on !CONFIG_SCHED_DEBUG as well sched/wait: Disambiguate wq_entry->task_list and wq_head->task_list naming sched/wait: Move bit_wait_table[] and related functionality from sched/core.c to sched/wait_bit.c sched/wait: Split out the wait_bit*() APIs from <linux/wait.h> into <linux/wait_bit.h> sched/wait: Re-adjust macro line continuation backslashes in <linux/wait.h> ...
2017-07-03Merge branch 'core-rcu-for-linus' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull RCU updates from Ingo Molnar: "The sole purpose of these changes is to shrink and simplify the RCU code base, which has suffered from creeping bloat over the past couple of years. The end result is a net removal of ~2700 lines of code: 79 files changed, 1496 insertions(+), 4211 deletions(-) Plus there's a marked reduction in the Kconfig space complexity as well, here's the number of matches on 'grep RCU' in the .config: before after x86-defconfig 17 15 x86-allmodconfig 33 20" * 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (86 commits) rcu: Remove RCU CPU stall warnings from Tiny RCU rcu: Remove event tracing from Tiny RCU rcu: Move RCU debug Kconfig options to kernel/rcu rcu: Move RCU non-debug Kconfig options to kernel/rcu rcu: Eliminate NOCBs CPU-state Kconfig options rcu: Remove debugfs tracing srcu: Remove Classic SRCU srcu: Fix rcutorture-statistics typo rcu: Remove SPARSE_RCU_POINTER Kconfig option rcu: Remove the now-obsolete PROVE_RCU_REPEATEDLY Kconfig option rcu: Remove typecheck() from RCU locking wrapper functions rcu: Remove #ifdef moving rcu_end_inkernel_boot from rcupdate.h rcu: Remove nohz_full full-system-idle state machine rcu: Remove the RCU_KTHREAD_PRIO Kconfig option rcu: Remove *_SLOW_* Kconfig options srcu: Use rnp->lock wrappers to replace explicit memory barriers rcu: Move rnp->lock wrappers for SRCU use rcu: Convert rnp->lock wrappers to macros for SRCU use rcu: Refactor #includes from include/linux/rcupdate.h bcm47xx: Fix build regression ...
2017-06-30sched/cputime: Refactor the cputime_adjust() codeGustavo A. R. Silva
Address a Coverity false positive, which is caused by overly convoluted code: Value assigned to variable 'utime' at line 619:utime = rtime; is overwritten at line 642:utime = rtime - stime; before it can be used. This makes such variable assignment useless. Remove this variable assignment and refactor the code related. Addresses-Coverity-ID: 1371643 Signed-off-by: Gustavo A. R. Silva <garsilva@embeddedor.com> Cc: Frans Klaver <fransklaver@gmail.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rik van Riel <riel@redhat.com> Cc: Stanislaw Gruszka <sgruszka@redhat.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Wanpeng Li <wanpeng.li@hotmail.com> Link: http://lkml.kernel.org/r/20170629184128.GA5271@embeddedgus Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-06-30sched/debug: Expose the number of RT/DL tasks that can migrateDaniel Bristot de Oliveira
Add the value of the rt_rq.rt_nr_migratory and dl_rq.dl_nr_migratory to the sched_debug output, for instance: rt_rq[0]: .rt_nr_running : 2 .rt_nr_migratory : 1 <--- Like this .rt_throttled : 0 .rt_time : 828.645877 .rt_runtime : 1000.000000 This is useful to debug problems related to the RT/DL schedulers. This also fixes the format of some variables, that were unsigned, rather than signed. Signed-off-by: Daniel Bristot de Oliveira <bristot@redhat.com> Cc: Clark Williams <williams@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Luis Claudio R. Goncalves <lgoncalv@redhat.com> Cc: Luiz Capitulino <lcapitulino@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-rt-users <linux-rt-users@vger.kernel.org> Link: http://lkml.kernel.org/r/7896f71cada54ee7dd8507bb666063a2e051c3d4.1498482127.git.bristot@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-06-29sched/numa: Hide numa_wake_affine() from UP buildThomas Gleixner
Stephen reported the following build warning in UP: kernel/sched/fair.c:2657:9: warning: 'struct sched_domain' declared inside parameter list ^ /home/sfr/next/next/kernel/sched/fair.c:2657:9: warning: its scope is only this definition or declaration, which is probably not what you want Hide the numa_wake_affine() inline stub on UP builds to get rid of it. Fixes: 3fed382b46ba ("sched/numa: Implement NUMA node level wake_affine()") Reported-by: Stephen Rothwell <sfr@canb.auug.org.au> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: Rik van Riel <riel@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org>
2017-06-24sched/fair: Remove effective_load()Rik van Riel
The effective_load() function was only used by the NUMA balancing code, and not by the regular load balancing code. Now that the NUMA balancing code no longer uses it either, get rid of it. Signed-off-by: Rik van Riel <riel@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mel Gorman <mgorman@suse.de> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: jhladky@redhat.com Cc: linux-kernel@vger.kernel.org Link: http://lkml.kernel.org/r/20170623165530.22514-5-riel@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-06-24sched/numa: Implement NUMA node level wake_affine()Rik van Riel
Since select_idle_sibling() can place a task anywhere on a socket, comparing loads between individual CPU cores makes no real sense for deciding whether to do an affine wakeup across sockets, either. Instead, compare the load between the sockets in a similar way the load balancer and the numa balancing code do. Signed-off-by: Rik van Riel <riel@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mel Gorman <mgorman@suse.de> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: jhladky@redhat.com Cc: linux-kernel@vger.kernel.org Link: http://lkml.kernel.org/r/20170623165530.22514-4-riel@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-06-24sched/fair: Simplify wake_affine() for the single socket caseRik van Riel
Then 'this_cpu' and 'prev_cpu' are in the same socket, select_idle_sibling() will do its thing regardless of the return value of wake_affine(). Just return true and don't look at all the other things. Signed-off-by: Rik van Riel <riel@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mel Gorman <mgorman@suse.de> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: jhladky@redhat.com Cc: linux-kernel@vger.kernel.org Link: http://lkml.kernel.org/r/20170623165530.22514-3-riel@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-06-24sched/numa: Override part of migrate_degrades_locality() when idle balancingRik van Riel
Several tests in the NAS benchmark seem to run a lot slower with NUMA balancing enabled, than with NUMA balancing disabled. The slower run time corresponds with increased idle time. Overriding the final test of migrate_degrades_locality (but still doing the other NUMA tests first) seems to improve performance of those benchmarks. Reported-by: Jirka Hladky <jhladky@redhat.com> Signed-off-by: Rik van Riel <riel@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mel Gorman <mgorman@suse.de> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-kernel@vger.kernel.org Link: http://lkml.kernel.org/r/20170623165530.22514-2-riel@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-06-23sched/rt: Move RT related code from sched/core.c to sched/rt.cNicolas Pitre
This helps making sched/core.c smaller and hopefully easier to understand and maintain. Signed-off-by: Nicolas Pitre <nico@linaro.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/20170621182203.30626-3-nicolas.pitre@linaro.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-06-23sched/deadline: Move DL related code from sched/core.c to sched/deadline.cNicolas Pitre
This helps making sched/core.c smaller and hopefully easier to understand and maintain. Signed-off-by: Nicolas Pitre <nico@linaro.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/20170621182203.30626-2-nicolas.pitre@linaro.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-06-23sched/cpuset: Only offer CONFIG_CPUSETS if SMP is enabledNicolas Pitre
Make CONFIG_CPUSETS=y depend on SMP as this feature makes no sense on UP. This allows for configuring out cpuset_cpumask_can_shrink() and task_can_attach() entirely, which shrinks the kernel a bit. Signed-off-by: Nicolas Pitre <nico@linaro.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/20170614171926.8345-2-nicolas.pitre@linaro.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-06-22sched/fair: Spare idle load balancing on nohz_full CPUsFrederic Weisbecker
Although idle load balancing obviously only concerns idle CPUs, it can be a disturbance on a busy nohz_full CPU. Indeed a CPU can only get rid of an idle load balancing duty once a tick fires while it runs a task and this can take a while on a nohz_full CPU. We could fix that and escape the idle load balancing duty from the very idle exit path but that would bring unecessary overhead. Lets just not bother and leave that job to housekeeping CPUs (those outside nohz_full range). The nohz_full CPUs simply don't want any disturbance. Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rik van Riel <riel@redhat.com> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/1497838322-10913-4-git-send-email-fweisbec@gmail.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-06-22sched/loadavg: Generalize "_idle" naming to "_nohz"Frederic Weisbecker
The loadavg naming code still assumes that nohz == idle whereas its code is actually handling well both nohz idle and nohz full. So lets fix the naming according to what the code actually does, to unconfuse the reader. Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Acked-by: Rik van Riel <riel@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/1497838322-10913-2-git-send-email-fweisbec@gmail.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-06-20Merge branch 'WIP.sched/core' into sched/coreIngo Molnar
Conflicts: kernel/sched/Makefile Pick up the waitqueue related renames - it didn't get much feedback, so it appears to be uncontroversial. Famous last words? ;-) Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-06-20sched/fair: WARN() and refuse to set buddy when !se->on_rqDaniel Axtens
If we set a next or last buddy for a se that is not on_rq, we will end up taking a NULL pointer dereference in wakeup_preempt_entity via pick_next_task_fair. Detect when we would be about to do that, throw a warning and then refuse to actually set it. This has been suggested at least twice: https://marc.info/?l=linux-kernel&m=146651668921468&w=2 https://lkml.org/lkml/2016/6/16/663 I recently had to debug a problem with these (we hadn't backported Konstantin's patches in this area) and this would have saved a lot of time/pain. Just do it. Signed-off-by: Daniel Axtens <dja@axtens.net> Cc: Ben Segall <bsegall@google.com> Cc: Konstantin Khlebnikov <khlebnikov@yandex-team.ru> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/20170510201139.16236-1-dja@axtens.net Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-06-20sched/debug: Fix SCHED_WARN_ON() to return a value on !CONFIG_SCHED_DEBUG as ↵Ingo Molnar
well This definition of SCHED_WARN_ON(): #define SCHED_WARN_ON(x) ((void)(x)) is not fully compatible with the 'real' WARN_ON_ONCE() primitive, as it has no return value, so it cannot be used in conditionals. Fix it. Cc: Daniel Axtens <dja@axtens.net> Cc: Konstantin Khlebnikov <khlebnikov@yandex-team.ru> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-06-20sched/wait: Disambiguate wq_entry->task_list and wq_head->task_list namingIngo Molnar
So I've noticed a number of instances where it was not obvious from the code whether ->task_list was for a wait-queue head or a wait-queue entry. Furthermore, there's a number of wait-queue users where the lists are not for 'tasks' but other entities (poll tables, etc.), in which case the 'task_list' name is actively confusing. To clear this all up, name the wait-queue head and entry list structure fields unambiguously: struct wait_queue_head::task_list => ::head struct wait_queue_entry::task_list => ::entry For example, this code: rqw->wait.task_list.next != &wait->task_list ... is was pretty unclear (to me) what it's doing, while now it's written this way: rqw->wait.head.next != &wait->entry ... which makes it pretty clear that we are iterating a list until we see the head. Other examples are: list_for_each_entry_safe(pos, next, &x->task_list, task_list) { list_for_each_entry(wq, &fence->wait.task_list, task_list) { ... where it's unclear (to me) what we are iterating, and during review it's hard to tell whether it's trying to walk a wait-queue entry (which would be a bug), while now it's written as: list_for_each_entry_safe(pos, next, &x->head, entry) { list_for_each_entry(wq, &fence->wait.head, entry) { Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-06-20sched/wait: Move bit_wait_table[] and related functionality from ↵Ingo Molnar
sched/core.c to sched/wait_bit.c The key hashed waitqueue data structures and their initialization was done in the main scheduler file for no good reason, move them to sched/wait_bit.c instead. Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-06-20sched/wait: Split out the wait_bit*() APIs from <linux/wait.h> into ↵Ingo Molnar
<linux/wait_bit.h> The wait_bit*() types and APIs are mixed into wait.h, but they are a pretty orthogonal extension of wait-queues. Furthermore, only about 50 kernel files use these APIs, while over 1000 use the regular wait-queue functionality. So clean up the main wait.h by moving the wait-bit functionality out of it, into a separate .h and .c file: include/linux/wait_bit.h for types and APIs kernel/sched/wait_bit.c for the implementation Update all header dependencies. This reduces the size of wait.h rather significantly, by about 30%. Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-06-20sched/wait: Standardize wait_bit_queue namingIngo Molnar
So wait-bit-queue head variables are often named: struct wait_bit_queue *q ... which is a bit ambiguous and super confusing, because they clearly suggest wait-queue head semantics and behavior (they rhyme with the old wait_queue_t *q naming), while they are extended wait-queue _entries_, not heads! They are misnomers in two ways: - the 'wait_bit_queue' leaves open the question of whether it's an entry or a head - the 'q' parameter and local variable naming falsely implies that it's a 'queue' - while it's an entry. This resulted in sometimes confusing cases such as: finish_wait(wq, &q->wait); where the 'q' is not a wait-queue head, but a wait-bit-queue entry. So improve this all by standardizing wait-bit-queue nomenclature similar to wait-queue head naming: struct wait_bit_queue => struct wait_bit_queue_entry q => wbq_entry Which makes it all a much clearer: struct wait_bit_queue_entry *wbq_entry ... and turns the former confusing piece of code into: finish_wait(wq_head, &wbq_entry->wq_entry; which IMHO makes it apparently clear what we are doing, without having to analyze the context of the code: we are adding a wait-queue entry to a regular wait-queue head, which entry is embedded in a wait-bit-queue entry. I'm not a big fan of acronyms, but repeating wait_bit_queue_entry in field and local variable names is too long, so Hopefully it's clear enough that 'wq_' prefixes stand for wait-queues, while 'wbq_' prefixes stand for wait-bit-queues. Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-06-20sched/wait: Standardize 'struct wait_bit_queue' wait-queue entry field nameIngo Molnar
Rename 'struct wait_bit_queue::wait' to ::wq_entry, to more clearly name it as a wait-queue entry. Propagate it to a couple of usage sites where the wait-bit-queue internals are exposed. Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-06-20sched/wait: Standardize internal naming of wait-queue headsIngo Molnar
The wait-queue head parameters and variables are named in a couple of ways, we have the following variants currently: wait_queue_head_t *q wait_queue_head_t *wq wait_queue_head_t *head In particular the 'wq' naming is ambiguous in the sense whether it's a wait-queue head or entry name - as entries were often named 'wait'. ( Not to mention the confusion of any readers coming over from workqueue-land. ) Standardize all this around a single, unambiguous parameter and variable name: struct wait_queue_head *wq_head which is easy to grep for and also rhymes nicely with the wait-queue entry naming: struct wait_queue_entry *wq_entry Also rename: struct __wait_queue_head => struct wait_queue_head ... and use this struct type to migrate from typedefs usage to 'struct' usage, which is more in line with existing kernel practices. Don't touch any external users and preserve the main wait_queue_head_t typedef. Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-06-20sched/wait: Standardize internal naming of wait-queue entriesIngo Molnar
So the various wait-queue entry variables in include/linux/wait.h and kernel/sched/wait.c are named in a colorfully inconsistent way: wait_queue_entry_t *wait wait_queue_entry_t *__wait (even in plain C code!) wait_queue_entry_t *q (!) wait_queue_entry_t *new (making anyone who knows C++ cringe) wait_queue_entry_t *old I think part of the reason for the inconsistency is the constant apparent confusion about what a wait queue 'head' versus 'entry' is. ( Some of the documentation talks about a 'wait descriptor', which is the wait-queue entry itself - further adding to the confusion. ) The most common name is 'wait', but that in itself is somewhat ambiguous as well, as it does not really make it clear whether it's a wait-queue entry or head. To improve all this name the wait-queue entry structure parameters and variables consistently and push through this naming into all the wait.h and wait.c code: struct wait_queue_entry *wq_entry The 'wq_' prefix makes it easy to grep for, and we also use the opportunity to move away from the typedef to a plain 'struct' naming: in the kernel we typically reserve typedefs for cases where a C structure is really small and somewhat opaque - such as pte_t. wait-queue entries are neither small nor opaque, so use the more standard 'struct xxx_entry' list management code nomenclature instead. ( We don't touch external users, and we preserve the typedef as well for actual wait-queue users, to reduce unnecessary churn. ) Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-06-20sched/wait: Rename wait_queue_t => wait_queue_entry_tIngo Molnar
Rename: wait_queue_t => wait_queue_entry_t 'wait_queue_t' was always a slight misnomer: its name implies that it's a "queue", but in reality it's a queue *entry*. The 'real' queue is the wait queue head, which had to carry the name. Start sorting this out by renaming it to 'wait_queue_entry_t'. This also allows the real structure name 'struct __wait_queue' to lose its double underscore and become 'struct wait_queue_entry', which is the more canonical nomenclature for such data types. Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-kernel@vger.kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-06-18Merge branch 'sched-urgent-for-linus' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull scheduler fixes from Thomas Gleixner: "Two small fixes for the schedulre core: - Use the proper switch_mm() variant in idle_task_exit() because that code is not called with interrupts disabled. - Fix a confusing typo in a printk" * 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: sched/core: Idle_task_exit() shouldn't use switch_mm_irqs_off() sched/fair: Fix typo in printk message
2017-06-15Merge branches 'pm-cpufreq', 'pm-cpuidle' and 'pm-devfreq'Rafael J. Wysocki
* pm-cpufreq: cpufreq: conservative: Allow down_threshold to take values from 1 to 10 Revert "cpufreq: schedutil: Reduce frequencies slower" * pm-cpuidle: cpuidle: dt: Add missing 'of_node_put()' * pm-devfreq: PM / devfreq: exynos-ppmu: Staticize event list PM / devfreq: exynos-ppmu: Handle return value of clk_prepare_enable PM / devfreq: exynos-nocp: Handle return value of clk_prepare_enable
2017-06-12Revert "cpufreq: schedutil: Reduce frequencies slower"Rafael J. Wysocki
Revert commit 39b64aa1c007 (cpufreq: schedutil: Reduce frequencies slower) that introduced unintentional changes in behavior leading to adverse effects on some systems. Reported-by: Viresh Kumar <viresh.kumar@linaro.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2017-06-11sched/core: Idle_task_exit() shouldn't use switch_mm_irqs_off()Andy Lutomirski
idle_task_exit() can be called with IRQs on x86 on and therefore should use switch_mm(), not switch_mm_irqs_off(). This doesn't seem to cause any problems right now, but it will confuse my upcoming TLB flush changes. Nonetheless, I think it should be backported because it's trivial. There won't be any meaningful performance impact because idle_task_exit() is only used when offlining a CPU. Signed-off-by: Andy Lutomirski <luto@kernel.org> Cc: Borislav Petkov <bp@suse.de> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: stable@vger.kernel.org Fixes: f98db6013c55 ("sched/core: Add switch_mm_irqs_off() and use it in the scheduler") Link: http://lkml.kernel.org/r/ca3d1a9fa93a0b49f5a8ff729eda3640fb6abdf9.1497034141.git.luto@kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-06-11sched/fair: Fix typo in printk messageMarcin Nowakowski
'schedstats' kernel parameter should be set to enable/disable, so correct the printk hint saying that it should be set to 'enable' rather than 'enabled' to enable scheduler tracepoints. Signed-off-by: Marcin Nowakowski <marcin.nowakowski@imgtec.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/1496995229-31245-1-git-send-email-marcin.nowakowski@imgtec.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-06-08sched: Rely on synchronize_rcu_mult() de-duplicationPaul E. McKenney
The synchronize_rcu_mult() function now detects duplicate requests for the same grace-period flavor and waits only once for each flavor. This commit therefore removes the ugly #ifdef from sched_cpu_deactivate() because synchronize_rcu_mult(call_rcu, call_rcu_sched) now does what the #ifdef used to be needed for. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de>
2017-06-08sched/idle: Add deferrable vmstat_updater backAubrey Li
Deferrable vmstat_updater was missing in commit: c1de45ca831a ("sched/idle: Add support for tasks that inject idle") Add it back. Signed-off-by: Aubrey Li <aubrey.li@linux.intel.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Aubrey Li <aubrey.li@intel.com> Cc: Christoph Lameter <cl@linux.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/1496803742-38274-1-git-send-email-aubrey.li@intel.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-06-08sched/core: Omit building stop_sched_class when !SMPNicolas Pitre
The stop class is invoked through stop_machine only. This is dead code on UP builds. Signed-off-by: Nicolas Pitre <nico@linaro.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/20170529210302.26868-3-nicolas.pitre@linaro.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-06-08sched/deadline: Use the revised wakeup rule for suspending constrained dl tasksDaniel Bristot de Oliveira
We have been facing some problems with self-suspending constrained deadline tasks. The main reason is that the original CBS was not designed for such sort of tasks. One problem reported by Xunlei Pang takes place when a task suspends, and then is awakened before the deadline, but so close to the deadline that its remaining runtime can cause the task to have an absolute density higher than allowed. In such situation, the original CBS assumes that the task is facing an early activation, and so it replenishes the task and set another deadline, one deadline in the future. This rule works fine for implicit deadline tasks. Moreover, it allows the system to adapt the period of a task in which the external event source suffered from a clock drift. However, this opens the window for bandwidth leakage for constrained deadline tasks. For instance, a task with the following parameters: runtime = 5 ms deadline = 7 ms [density] = 5 / 7 = 0.71 period = 1000 ms If the task runs for 1 ms, and then suspends for another 1ms, it will be awakened with the following parameters: remaining runtime = 4 laxity = 5 presenting a absolute density of 4 / 5 = 0.80. In this case, the original CBS would assume the task had an early wakeup. Then, CBS will reset the runtime, and the absolute deadline will be postponed by one relative deadline, allowing the task to run. The problem is that, if the task runs this pattern forever, it will keep receiving bandwidth, being able to run 1ms every 2ms. Following this behavior, the task would be able to run 500 ms in 1 sec. Thus running more than the 5 ms / 1 sec the admission control allowed it to run. Trying to address the self-suspending case, Luca Abeni, Giuseppe Lipari, and Juri Lelli [1] revisited the CBS in order to deal with self-suspending tasks. In the new approach, rather than replenishing/postponing the absolute deadline, the revised wakeup rule adjusts the remaining runtime, reducing it to fit into the allowed density. A revised version of the idea is: At a given time t, the maximum absolute density of a task cannot be higher than its relative density, that is: runtime / (deadline - t) <= dl_runtime / dl_deadline Knowing the laxity of a task (deadline - t), it is possible to move it to the other side of the equality, thus enabling to define max remaining runtime a task can use within the absolute deadline, without over-running the allowed density: runtime = (dl_runtime / dl_deadline) * (deadline - t) For instance, in our previous example, the task could still run: runtime = ( 5 / 7 ) * 5 runtime = 3.57 ms Without causing damage for other deadline tasks. It is note worthy that the laxity cannot be negative because that would cause a negative runtime. Thus, this patch depends on the patch: df8eac8cafce ("sched/deadline: Throttle a constrained deadline task activated after the deadline") Which throttles a constrained deadline task activated after the deadline. Finally, it is also possible to use the revised wakeup rule for all other tasks, but that would require some more discussions about pros and cons. Reported-by: Xunlei Pang <xpang@redhat.com> Signed-off-by: Daniel Bristot de Oliveira <bristot@redhat.com> [peterz: replaced dl_is_constrained with dl_is_implicit] Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Juri Lelli <juri.lelli@arm.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Luca Abeni <luca.abeni@santannapisa.it> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Romulo Silva de Oliveira <romulo.deoliveira@ufsc.br> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Tommaso Cucinotta <tommaso.cucinotta@sssup.it> Link: http://lkml.kernel.org/r/5c800ab3a74a168a84ee5f3f84d12a02e11383be.1495803804.git.bristot@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-06-08sched/deadline: Zero out positive runtime after throttling constrained tasksXunlei Pang
When a contrained task is throttled by dl_check_constrained_dl(), it may carry the remaining positive runtime, as a result when dl_task_timer() fires and calls replenish_dl_entity(), it will not be replenished correctly due to the positive dl_se->runtime. This patch assigns its runtime to 0 if positive after throttling. Signed-off-by: Xunlei Pang <xlpang@redhat.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Daniel Bristot de Oliveira <bristot@redhat.com> Cc: Juri Lelli <juri.lelli@arm.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Luca Abeni <luca.abeni@santannapisa.it> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Thomas Gleixner <tglx@linutronix.de> Fixes: df8eac8cafce ("sched/deadline: Throttle a constrained deadline task activated after the deadline) Link: http://lkml.kernel.org/r/1494421417-27550-1-git-send-email-xlpang@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-06-08sched/deadline: Reclaim bandwidth not used by dl tasksLuca Abeni
This commit introduces a per-runqueue "extra utilization" that can be reclaimed by deadline tasks. In this way, the maximum fraction of CPU time that can reclaimed by deadline tasks is fixed (and configurable) and does not depend on the total deadline utilization. The GRUB accounting rule is modified to add this "extra utilization" to the inactive utilization of the runqueue, and to avoid reclaiming more than a maximum fraction of the CPU time. Tested-by: Daniel Bristot de Oliveira <bristot@redhat.com> Signed-off-by: Luca Abeni <luca.abeni@santannapisa.it> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Claudio Scordino <claudio@evidence.eu.com> Cc: Joel Fernandes <joelaf@google.com> Cc: Juri Lelli <juri.lelli@arm.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mathieu Poirier <mathieu.poirier@linaro.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Tommaso Cucinotta <tommaso.cucinotta@sssup.it> Link: http://lkml.kernel.org/r/1495138417-6203-10-git-send-email-luca.abeni@santannapisa.it Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-06-08sched/deadline: Base GRUB reclaiming on the inactive utilizationLuca Abeni
Instead of decreasing the runtime as "dq = -Uact dt" (eventually divided by the maximum utilization available for deadline tasks), decrease it as "dq = -max{u, (1 - Uinact)} dt", where u is the task utilization and Uinact is the "inactive utilization". In this way, the maximum fraction of CPU time that can be reclaimed is given by the total utilization of deadline tasks. This approach solves a fairness issue with "traditional" global GRUB reclaiming: using the traditional GRUB algorithm, if tasks are allocated to the various cores in a non-uniform way, the reclaiming mechanism allows some tasks to reclaim more time than others. This issue is visible starting 11 time-consuming tasks with runtime 10ms and period 30ms (total utilization 3.666) on a 4-cores system: some tasks will receive much more than the reserved runtime (thanks to the reclaiming mechanism), while other tasks will receive less than the reserved runtime. Tested-by: Daniel Bristot de Oliveira <bristot@redhat.com> Signed-off-by: Luca Abeni <luca.abeni@santannapisa.it> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Claudio Scordino <claudio@evidence.eu.com> Cc: Joel Fernandes <joelaf@google.com> Cc: Juri Lelli <juri.lelli@arm.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mathieu Poirier <mathieu.poirier@linaro.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Tommaso Cucinotta <tommaso.cucinotta@sssup.it> Link: http://lkml.kernel.org/r/1495138417-6203-9-git-send-email-luca.abeni@santannapisa.it Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-06-08sched/deadline: Track the "total rq utilization" tooLuca Abeni
The total rq utilization is defined as the sum of the utilisations of tasks that are "assigned" to a runqueue, independently from their state (TASK_RUNNING or blocked) Tested-by: Daniel Bristot de Oliveira <bristot@redhat.com> Signed-off-by: Luca Abeni <luca.abeni@santannapisa.it> Signed-off-by: Claudio Scordino <claudio@evidence.eu.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Joel Fernandes <joelaf@google.com> Cc: Juri Lelli <juri.lelli@arm.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mathieu Poirier <mathieu.poirier@linaro.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Tommaso Cucinotta <tommaso.cucinotta@sssup.it> Link: http://lkml.kernel.org/r/1495138417-6203-8-git-send-email-luca.abeni@santannapisa.it Signed-off-by: Ingo Molnar <mingo@kernel.org>