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2024-02-14rcu: Rename jiffies_till_flush to jiffies_lazy_flushFrederic Weisbecker
The variable name jiffies_till_flush is too generic and therefore: * It may shadow a global variable * It doesn't tell on what it operates Make the name more precise, along with the related APIs. Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org> Signed-off-by: Frederic Weisbecker <frederic@kernel.org> Reviewed-by: Paul E. McKenney <paulmck@kernel.org> Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
2023-07-14rcuscale: Move rcu_scale_writer() schedule_timeout_uninterruptible() to _idle()Zqiang
The rcuscale.holdoff module parameter can be used to delay the start of rcu_scale_writer() kthread. However, the hung-task timeout will trigger when the timeout specified by rcuscale.holdoff is greater than hung_task_timeout_secs: runqemu kvm nographic slirp qemuparams="-smp 4 -m 2048M" bootparams="rcuscale.shutdown=0 rcuscale.holdoff=300" [ 247.071753] INFO: task rcu_scale_write:59 blocked for more than 122 seconds. [ 247.072529] Not tainted 6.4.0-rc1-00134-gb9ed6de8d4ff #7 [ 247.073400] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. [ 247.074331] task:rcu_scale_write state:D stack:30144 pid:59 ppid:2 flags:0x00004000 [ 247.075346] Call Trace: [ 247.075660] <TASK> [ 247.075965] __schedule+0x635/0x1280 [ 247.076448] ? __pfx___schedule+0x10/0x10 [ 247.076967] ? schedule_timeout+0x2dc/0x4d0 [ 247.077471] ? __pfx_lock_release+0x10/0x10 [ 247.078018] ? enqueue_timer+0xe2/0x220 [ 247.078522] schedule+0x84/0x120 [ 247.078957] schedule_timeout+0x2e1/0x4d0 [ 247.079447] ? __pfx_schedule_timeout+0x10/0x10 [ 247.080032] ? __pfx_rcu_scale_writer+0x10/0x10 [ 247.080591] ? __pfx_process_timeout+0x10/0x10 [ 247.081163] ? __pfx_sched_set_fifo_low+0x10/0x10 [ 247.081760] ? __pfx_rcu_scale_writer+0x10/0x10 [ 247.082287] rcu_scale_writer+0x6b1/0x7f0 [ 247.082773] ? mark_held_locks+0x29/0xa0 [ 247.083252] ? __pfx_rcu_scale_writer+0x10/0x10 [ 247.083865] ? __pfx_rcu_scale_writer+0x10/0x10 [ 247.084412] kthread+0x179/0x1c0 [ 247.084759] ? __pfx_kthread+0x10/0x10 [ 247.085098] ret_from_fork+0x2c/0x50 [ 247.085433] </TASK> This commit therefore replaces schedule_timeout_uninterruptible() with schedule_timeout_idle(). Signed-off-by: Zqiang <qiang.zhang1211@gmail.com> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2023-07-14rcuscale: fix building with RCU_TINYArnd Bergmann
Both the CONFIG_TASKS_RCU and CONFIG_TASKS_RUDE_RCU options are broken when RCU_TINY is enabled as well, as some functions are missing a declaration. In file included from kernel/rcu/update.c:649: kernel/rcu/tasks.h:1271:21: error: no previous prototype for 'get_rcu_tasks_rude_gp_kthread' [-Werror=missing-prototypes] 1271 | struct task_struct *get_rcu_tasks_rude_gp_kthread(void) | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~ kernel/rcu/rcuscale.c:330:27: error: 'get_rcu_tasks_rude_gp_kthread' undeclared here (not in a function); did you mean 'get_rcu_tasks_trace_gp_kthread'? 330 | .rso_gp_kthread = get_rcu_tasks_rude_gp_kthread, | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~ | get_rcu_tasks_trace_gp_kthread In file included from /home/arnd/arm-soc/kernel/rcu/update.c:649: kernel/rcu/tasks.h:1113:21: error: no previous prototype for 'get_rcu_tasks_gp_kthread' [-Werror=missing-prototypes] 1113 | struct task_struct *get_rcu_tasks_gp_kthread(void) | ^~~~~~~~~~~~~~~~~~~~~~~~ Also, building with CONFIG_TASKS_RUDE_RCU but not CONFIG_TASKS_RCU is broken because of some missing stub functions: kernel/rcu/rcuscale.c:322:27: error: 'tasks_scale_read_lock' undeclared here (not in a function); did you mean 'srcu_scale_read_lock'? 322 | .readlock = tasks_scale_read_lock, | ^~~~~~~~~~~~~~~~~~~~~ | srcu_scale_read_lock kernel/rcu/rcuscale.c:323:27: error: 'tasks_scale_read_unlock' undeclared here (not in a function); did you mean 'srcu_scale_read_unlock'? 323 | .readunlock = tasks_scale_read_unlock, | ^~~~~~~~~~~~~~~~~~~~~~~ | srcu_scale_read_unlock Move the declarations outside of the RCU_TINY #ifdef and duplicate the shared stub functions to address all of the above. Fixes: 88d7ff818f0ce ("rcuscale: Add RCU Tasks Rude testing") Fixes: 755f1c5eb416b ("rcuscale: Measure RCU Tasks Trace grace-period kthread CPU time") Signed-off-by: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2023-07-14rcuscale: Add RCU Tasks Rude testingPaul E. McKenney
Add a "tasks-rude" option to the rcuscale.scale_type module parameter. Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2023-07-14rcuscale: Measure RCU Tasks Trace grace-period kthread CPU timePaul E. McKenney
This commit causes RCU Tasks Trace to output the CPU time consumed by its grace-period kthread. The CPU time is whatever is in the designated task's current->stime field, and thus is controlled by whatever CPU-time accounting scheme is in effect. This output appears in microseconds as follows on the console: rcu_scale: Grace-period kthread CPU time: 42367.037 [ paulmck: Apply Willy Tarreau feedback. ] Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2023-07-14rcuscale: Measure grace-period kthread CPU timePaul E. McKenney
This commit adds the ability to output the CPU time consumed by the grace-period kthread for the RCU variant under test. The CPU time is whatever is in the designated task's current->stime field, and thus is controlled by whatever CPU-time accounting scheme is in effect. This output appears in microseconds as follows on the console: rcu_scale: Grace-period kthread CPU time: 42367.037 [ paulmck: Apply feedback from Stephen Rothwell and kernel test robot. ] Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Tested-by: Yujie Liu <yujie.liu@intel.com>
2023-07-14rcuscale: Print out full set of kfree_rcu parametersPaul E. McKenney
Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Cc: Uladzislau Rezki (Sony) <urezki@gmail.com>
2023-07-14rcuscale: Print out full set of module parametersPaul E. McKenney
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2023-07-14rcuscale: Add minruntime module parameterPaul E. McKenney
By default, rcuscale collects only 100 points of data per writer, but arranging for all kthreads to be actively collecting (if not recording) data during the time that any kthread might be recording. This works well, but does not allow much time to bring external performance tools to bear. This commit therefore adds a minruntime module parameter that specifies a minimum data-collection interval in seconds. Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2023-07-14rcuscale: Fix gp_async_max typo: s/reader/writer/Paul E. McKenney
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2023-07-14rcuscale: Permit blocking delays between writersPaul E. McKenney
Some workloads do isolated RCU work, and this can affect operation latencies. This commit therefore adds a writer_holdoff_jiffies module parameter that causes writers to block for the specified number of jiffies between each pair of consecutive write-side operations. Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2023-05-11rcu/rcuscale: Stop kfree_scale_thread thread(s) after unloading rcuscaleQiuxu Zhuo
Running the 'kfree_rcu_test' test case [1] results in a splat [2]. The root cause is the kfree_scale_thread thread(s) continue running after unloading the rcuscale module. This commit fixes that isue by invoking kfree_scale_cleanup() from rcu_scale_cleanup() when removing the rcuscale module. [1] modprobe rcuscale kfree_rcu_test=1 // After some time rmmod rcuscale rmmod torture [2] BUG: unable to handle page fault for address: ffffffffc0601a87 #PF: supervisor instruction fetch in kernel mode #PF: error_code(0x0010) - not-present page PGD 11de4f067 P4D 11de4f067 PUD 11de51067 PMD 112f4d067 PTE 0 Oops: 0010 [#1] PREEMPT SMP NOPTI CPU: 1 PID: 1798 Comm: kfree_scale_thr Not tainted 6.3.0-rc1-rcu+ #1 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 0.0.0 02/06/2015 RIP: 0010:0xffffffffc0601a87 Code: Unable to access opcode bytes at 0xffffffffc0601a5d. RSP: 0018:ffffb25bc2e57e18 EFLAGS: 00010297 RAX: 0000000000000000 RBX: ffffffffc061f0b6 RCX: 0000000000000000 RDX: 0000000000000000 RSI: ffffffff962fd0de RDI: ffffffff962fd0de RBP: ffffb25bc2e57ea8 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000001 R11: 0000000000000001 R12: 0000000000000000 R13: 0000000000000000 R14: 000000000000000a R15: 00000000001c1dbe FS: 0000000000000000(0000) GS:ffff921fa2200000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: ffffffffc0601a5d CR3: 000000011de4c006 CR4: 0000000000370ee0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: <TASK> ? kvfree_call_rcu+0xf0/0x3a0 ? kthread+0xf3/0x120 ? kthread_complete_and_exit+0x20/0x20 ? ret_from_fork+0x1f/0x30 </TASK> Modules linked in: rfkill sunrpc ... [last unloaded: torture] CR2: ffffffffc0601a87 ---[ end trace 0000000000000000 ]--- Fixes: e6e78b004fa7 ("rcuperf: Add kfree_rcu() performance Tests") Reviewed-by: Davidlohr Bueso <dave@stgolabs.net> Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org> Signed-off-by: Qiuxu Zhuo <qiuxu.zhuo@intel.com> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2023-05-11rcu/rcuscale: Move rcu_scale_*() after kfree_scale_cleanup()Qiuxu Zhuo
This code-movement-only commit moves the rcu_scale_cleanup() and rcu_scale_shutdown() functions to follow kfree_scale_cleanup(). This is code movement is in preparation for a bug-fix patch that invokes kfree_scale_cleanup() from rcu_scale_cleanup(). Signed-off-by: Qiuxu Zhuo <qiuxu.zhuo@intel.com> Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org>
2023-04-05Merge branches 'rcu/staging-core', 'rcu/staging-docs' and ↵Joel Fernandes (Google)
'rcu/staging-kfree', remote-tracking branches 'paul/srcu-cf.2023.04.04a', 'fbq/rcu/lockdep.2023.03.27a' and 'fbq/rcu/rcutorture.2023.03.20a' into rcu/staging
2023-04-05rcuscale: Rename kfree_rcu() to kfree_rcu_mightsleep()Uladzislau Rezki (Sony)
The kfree_rcu() and kvfree_rcu() macros' single-argument forms are deprecated. Therefore switch to the new kfree_rcu_mightsleep() and kvfree_rcu_mightsleep() variants. The goal is to avoid accidental use of the single-argument forms, which can introduce functionality bugs in atomic contexts and latency bugs in non-atomic contexts. Acked-by: Joel Fernandes (Google) <joel@joelfernandes.org> Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com> Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
2023-03-20rcuscale: Move shutdown from wait_event() to wait_event_idle()Paul E. McKenney
The rcu_scale_shutdown() and kfree_scale_shutdown() kthreads/functions use wait_event() to wait for the rcuscale test to complete. However, each updater thread in such a test waits for at least 100 grace periods. If each grace period takes more than 1.2 seconds, which is long, but not insanely so, this can trigger the hung-task timeout. This commit therefore replaces those wait_event() calls with calls to wait_event_idle(), which do not trigger the hung-task timeout. Reported-by: kernel test robot <yujie.liu@intel.com> Reported-by: Liam Howlett <liam.howlett@oracle.com> Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Tested-by: Yujie Liu <yujie.liu@intel.com> Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
2022-11-29rcu/rcuscale: Use call_rcu_hurry() for async reader testJoel Fernandes (Google)
rcuscale uses call_rcu() to queue async readers. With recent changes to save power, the test will have fewer async readers in flight. Use the call_rcu_hurry() API instead to revert to the old behavior. [ paulmck: Apply s/call_rcu_flush/call_rcu_hurry/ feedback from Tejun Heo. ] Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2022-11-29rcuscale: Add laziness and kfree testsJoel Fernandes (Google)
This commit adds 2 tests to rcuscale. The first one is a startup test to check whether we are not too lazy or too hard working. The second one causes kfree_rcu() itself to use call_rcu() and checks memory pressure. Testing indicates that the new call_rcu() keeps memory pressure under control roughly as well as does kfree_rcu(). [ paulmck: Apply checkpatch feedback. ] Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2022-06-21rcuscale: Fix smp_processor_id()-in-preemptible warningsZqiang
Systems built with CONFIG_DEBUG_PREEMPT=y can trigger the following BUG while running the rcuscale performance test: BUG: using smp_processor_id() in preemptible [00000000] code: rcu_scale_write/69 CPU: 0 PID: 66 Comm: rcu_scale_write Not tainted 5.18.0-rc7-next-20220517-yoctodev-standard+ caller is debug_smp_processor_id+0x17/0x20 Call Trace: <TASK> dump_stack_lvl+0x49/0x5e dump_stack+0x10/0x12 check_preemption_disabled+0xdf/0xf0 debug_smp_processor_id+0x17/0x20 rcu_scale_writer+0x2b5/0x580 kthread+0x177/0x1b0 ret_from_fork+0x22/0x30 </TASK> Reproduction method: runqemu kvm slirp nographic qemuparams="-m 4096 -smp 8" bootparams="isolcpus=2,3 nohz_full=2,3 rcu_nocbs=2,3 rcutree.dump_tree=1 rcuscale.shutdown=false rcuscale.gp_async=true" -d The problem is that the rcu_scale_writer() kthreads fail to set the PF_NO_SETAFFINITY flags, which causes is_percpu_thread() to assume that the kthread's affinity might change at any time, thus the BUG noted above. This commit therefore causes rcu_scale_writer() to set PF_NO_SETAFFINITY in its kthread's ->flags field, thus preventing this BUG. Signed-off-by: Zqiang <qiang1.zhang@intel.com> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2022-04-20rcuscale: Allow rcuscale without RCU Tasks Rude/TracePaul E. McKenney
Currently, a CONFIG_PREEMPT_NONE=y kernel substitutes normal RCU for RCU Tasks Rude and RCU Tasks Trace. Unless that kernel builds rcuscale, whether built-in or as a module, in which case these RCU Tasks flavors are (unnecessarily) built in. This both increases kernel size and increases the complexity of certain tracing operations. This commit therefore decouples the presence of rcuscale from the presence of RCU Tasks Rude and RCU Tasks Trace. Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2022-04-20rcuscale: Allow rcuscale without RCU TasksPaul E. McKenney
Currently, a CONFIG_PREEMPT_NONE=y kernel substitutes normal RCU for RCU Tasks. Unless that kernel builds rcuscale, whether built-in or as a module, in which case RCU Tasks is (unnecessarily) built. This both increases kernel size and increases the complexity of certain tracing operations. This commit therefore decouples the presence of rcuscale from the presence of RCU Tasks. Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2021-12-07rcuscale: Always log error messageLi Zhijian
Unconditionally log messages corresponding to errors. Acked-by: Davidlohr Bueso <dbueso@suse.de> Signed-off-by: Li Zhijian <zhijianx.li@intel.com> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2021-09-13rcuscale: Warn on individual rcu_scale_init() error conditionsPaul E. McKenney
When running rcuscale as a module, any rcu_scale_init() issues will be reflected in the error code from modprobe or insmod, as the case may be. However, these error codes are not available when running rcuscale built-in, for example, when using the kvm.sh script. This commit therefore adds WARN_ON_ONCE() to allow distinguishing rcu_scale_init() errors when running rcuscale built-in. Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2021-07-27rcuscale: Console output claims too few grace periodsJiangong.Han
The rcuscale console output claims N grace periods, numbered from zero to N, which means that there were really N+1 grace periods. The root cause of this bug is that rcu_scale_writer() stores the number of the last grace period (numbered from zero) into writer_n_durations[me] instead of the number of grace periods. This commit therefore assigns the actual number of grace periods to writer_n_durations[me], and also makes the corresponding adjustment to the loop outputting per-grace-period measurements. Sample of old console output: rcu-scale: writer 0 gps: 133 ...... rcu-scale: 0 writer-duration: 0 44003961 rcu-scale: 0 writer-duration: 1 32003582 ...... rcu-scale: 0 writer-duration: 132 28004391 rcu-scale: 0 writer-duration: 133 27996410 Sample of new console output: rcu-scale: writer 0 gps: 134 ...... rcu-scale: 0 writer-duration: 0 44003961 rcu-scale: 0 writer-duration: 1 32003582 ...... rcu-scale: 0 writer-duration: 132 28004391 rcu-scale: 0 writer-duration: 133 27996410 Signed-off-by: Jiangong.Han <jiangong.han@windriver.com> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2021-03-08rcuscale: Add kfree_rcu() single-argument scale testUladzislau Rezki (Sony)
The single-argument variant of kfree_rcu() is currently not tested by any member of the rcutoture test suite. This commit therefore adds rcuscale code to test it. This testing is controlled by two new boolean module parameters, kfree_rcu_test_single and kfree_rcu_test_double. If one is set and the other not, only the corresponding variant is tested, otherwise both are tested, with the variant to be tested determined randomly on each invocation. Both of these module parameters are initialized to false, so setting either to true will test only that variant. Suggested-by: Paul E. McKenney <paulmck@kernel.org> Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2020-11-06rcuscale: Prevent hangs for invalid argumentsPaul E. McKenney
If an rcuscale torture-test run is given a bad kvm.sh argument, the test will complain to the console, which is good. What is bad is that from the user's perspective, it will just hang for the time specified by the --duration argument. This commit therefore forces an immediate kernel shutdown if a rcu_scale_init()-time error occurs, thus avoiding the appearance of a hang. It also forces a console splat in this case to clearly indicate the presence of an error. Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2020-11-06rcuscale: Add RCU Tasks TracePaul E. McKenney
This commit adds the ability to test performance and scalability of RCU Tasks Trace updaters. Reported-by: Alexei Starovoitov <alexei.starovoitov@gmail.com> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2020-08-24rcuperf: Change rcuperf to rcuscalePaul E. McKenney
This commit further avoids conflation of rcuperf with the kernel's perf feature by renaming kernel/rcu/rcuperf.c to kernel/rcu/rcuscale.c, and also by similarly renaming the functions and variables inside this file. This has the side effect of changing the names of the kernel boot parameters, so kernel-parameters.txt and ver_functions.sh are also updated. The rcutorture --torture type was also updated from rcuperf to rcuscale. [ paulmck: Fix bugs located by Stephen Rothwell. ] Reported-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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