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authorFrederic Weisbecker <frederic@kernel.org>2017-10-31 04:18:34 +0100
committerIngo Molnar <mingo@kernel.org>2017-10-31 10:29:39 +0100
commitb0d40d2b22fe48cfcbbfb137fd198be0a1cd8a85 (patch)
tree32066cf080c3edb79e356e322795de92249e1e4f /Documentation/admin-guide
parent150dfee95feb913876ced5cc559a342384e8ea97 (diff)
sched/isolation: Document isolcpus= boot parameter flags, mark it deprecated
Document the latest updates on the isolcpus= boot option. While at it, let's also fix the details about the preferred way to isolate a set of CPUs from the scheduler general domains. Cpusets offer a much better interface to achieve that. Signed-off-by: Frederic Weisbecker <frederic@kernel.org> Acked-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Peter Zijlstra <peterz@infradead.org> Cc: Chris Metcalf <cmetcalf@mellanox.com> Cc: Christoph Lameter <cl@linux.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Luiz Capitulino <lcapitulino@redhat.com> Cc: Mike Galbraith <efault@gmx.de> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Rik van Riel <riel@redhat.com> Cc: Wanpeng Li <kernellwp@gmail.com> Link: http://lkml.kernel.org/r/1509419914-16179-1-git-send-email-frederic@kernel.org [ Clarified the text some more, marked the boot option deprecated. ] Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'Documentation/admin-guide')
-rw-r--r--Documentation/admin-guide/kernel-parameters.txt39
1 files changed, 26 insertions, 13 deletions
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 6b99c8b77c59..17eb0234d5be 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -1727,20 +1727,33 @@
isapnp= [ISAPNP]
Format: <RDP>,<reset>,<pci_scan>,<verbosity>
- isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler.
- The argument is a cpu list, as described above.
+ isolcpus= [KNL,SMP] Isolate a given set of CPUs from disturbance.
+ [Deprecated - use cpusets instead]
+ Format: [flag-list,]<cpu-list>
+
+ Specify one or more CPUs to isolate from disturbances
+ specified in the flag list (default: domain):
+
+ nohz
+ Disable the tick when a single task runs.
+ domain
+ Isolate from the general SMP balancing and scheduling
+ algorithms. Note that performing domain isolation this way
+ is irreversible: it's not possible to bring back a CPU to
+ the domains once isolated through isolcpus. It's strongly
+ advised to use cpusets instead to disable scheduler load
+ balancing through the "cpuset.sched_load_balance" file.
+ It offers a much more flexible interface where CPUs can
+ move in and out of an isolated set anytime.
+
+ You can move a process onto or off an "isolated" CPU via
+ the CPU affinity syscalls or cpuset.
+ <cpu number> begins at 0 and the maximum value is
+ "number of CPUs in system - 1".
+
+ The format of <cpu-list> is described above.
+
- This option can be used to specify one or more CPUs
- to isolate from the general SMP balancing and scheduling
- algorithms. You can move a process onto or off an
- "isolated" CPU via the CPU affinity syscalls or cpuset.
- <cpu number> begins at 0 and the maximum value is
- "number of CPUs in system - 1".
-
- This option is the preferred way to isolate CPUs. The
- alternative -- manually setting the CPU mask of all
- tasks in the system -- can cause problems and
- suboptimal load balancer performance.
iucv= [HW,NET]