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sched/isolation: Document isolcpus= boot parameter flags, mark it deprecated

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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>
This commit is contained in:
Frederic Weisbecker 2017-10-31 04:18:34 +01:00 committed by Ingo Molnar
parent 150dfee95f
commit b0d40d2b22
1 changed files with 25 additions and 12 deletions
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33
Documentation/admin-guide/kernel-parameters.txt
View File

@ -1727,20 +1727,33 @@
isapnp= [ISAPNP] isapnp= [ISAPNP]
Format: <RDP>,<reset>,<pci_scan>,<verbosity> Format: <RDP>,<reset>,<pci_scan>,<verbosity>
isolcpus= [KNL,SMP] Isolate CPUs from the general scheduler. isolcpus= [KNL,SMP] Isolate a given set of CPUs from disturbance.
The argument is a cpu list, as described above. [Deprecated - use cpusets instead]
Format: [flag-list,]<cpu-list>
This option can be used to specify one or more CPUs Specify one or more CPUs to isolate from disturbances
to isolate from the general SMP balancing and scheduling specified in the flag list (default: domain):
algorithms. You can move a process onto or off an
"isolated" CPU via the CPU affinity syscalls or cpuset. 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 <cpu number> begins at 0 and the maximum value is
"number of CPUs in system - 1". "number of CPUs in system - 1".
This option is the preferred way to isolate CPUs. The The format of <cpu-list> is described above.
alternative -- manually setting the CPU mask of all
tasks in the system -- can cause problems and
suboptimal load balancer performance.
iucv= [HW,NET] iucv= [HW,NET]