diff options
| author | Waiman Long <longman@redhat.com> | 2024-10-30 13:52:51 -0400 |
|---|---|---|
| committer | Peter Zijlstra <peterz@infradead.org> | 2024-12-02 12:24:28 +0100 |
| commit | 1174b9344bc7e7989439cad207fcd94eaab028db (patch) | |
| tree | 8fcc42f5069ffdef87f767215b27d63be80a2632 | |
| parent | ae5c677729e99b8cb3e6252aaa9b72a92985d203 (diff) | |
sched/isolation: Make "isolcpus=nohz" equivalent to "nohz_full"
The "isolcpus=nohz" boot parameter and flag were used to disable tick
when running a single task. Nowsdays, this "nohz" flag is seldomly used
as it is included as part of the "nohz_full" parameter. Extend this
flag to cover other kernel noises disabled by the "nohz_full" parameter
to make them equivalent. This also eliminates the need to use both the
"isolcpus" and the "nohz_full" parameters to fully isolated a given
set of CPUs.
Suggested-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Frederic Weisbecker <frederic@kernel.org>
Link: https://lore.kernel.org/r/20241030175253.125248-3-longman@redhat.com
| -rw-r--r-- | Documentation/admin-guide/kernel-parameters.txt | 4 | ||||
| -rw-r--r-- | kernel/sched/isolation.c | 6 |
2 files changed, 8 insertions, 2 deletions
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index 3872bc6ec49d..3fa0b4e65275 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -2432,7 +2432,9 @@ specified in the flag list (default: domain): nohz - Disable the tick when a single task runs. + Disable the tick when a single task runs as well as + disabling other kernel noises like having RCU callbacks + offloaded. This is equivalent to the nohz_full parameter. A residual 1Hz tick is offloaded to workqueues, which you need to affine to housekeeping through the global diff --git a/kernel/sched/isolation.c b/kernel/sched/isolation.c index 5345e11f3d44..6a686322ce3c 100644 --- a/kernel/sched/isolation.c +++ b/kernel/sched/isolation.c @@ -209,9 +209,13 @@ static int __init housekeeping_isolcpus_setup(char *str) int len; while (isalpha(*str)) { + /* + * isolcpus=nohz is equivalent to nohz_full. + */ if (!strncmp(str, "nohz,", 5)) { str += 5; - flags |= HK_FLAG_TICK; + flags |= HK_FLAG_TICK | HK_FLAG_WQ | HK_FLAG_TIMER | + HK_FLAG_RCU | HK_FLAG_MISC | HK_FLAG_KTHREAD; continue; } |