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| author |   Rik van Riel <riel@surriel.com> | 2024-11-08 19:27:50 -0500 |
|---|---|---|
| committer |   Ingo Molnar <mingo@kernel.org> | 2024-11-13 03:42:41 +0100 |
| commit | 7e33001b8b9a78062679e0fdf5b0842a49063135 (patch) | |
| tree | a4d43a057f795ab7c76358c7a80ff5a57b1526c2 | |
| parent | Merge tag 'v6.12-rc7' into x86/mm, to pick up fixes before applying new patches (diff) | |
| download | wireguard-linux-7e33001b8b9a78062679e0fdf5b0842a49063135.tar.xz wireguard-linux-7e33001b8b9a78062679e0fdf5b0842a49063135.zip | |
x86/mm/tlb: Put cpumask_test_cpu() check in switch_mm_irqs_off() under CONFIG_DEBUG_VM
On a web server workload, the cpumask_test_cpu() inside the
WARN_ON_ONCE() in the 'prev == next branch' takes about 17% of
all the CPU time of switch_mm_irqs_off().
On a large fleet, this WARN_ON_ONCE() has not fired in at least
a month, possibly never.
Move this test under CONFIG_DEBUG_VM so it does not get compiled
in production kernels.
Signed-off-by: Rik van Riel <riel@surriel.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lore.kernel.org/r/20241109003727.3958374-4-riel@surriel.com
Diffstat (limited to '')
| -rw-r--r-- | arch/x86/mm/tlb.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/arch/x86/mm/tlb.c b/arch/x86/mm/tlb.c index 86593d1b787d..b0d5a644fc84 100644 --- a/arch/x86/mm/tlb.c +++ b/arch/x86/mm/tlb.c @@ -568,7 +568,7 @@ void switch_mm_irqs_off(struct mm_struct *unused, struct mm_struct *next, * mm_cpumask. The TLB shootdown code can figure out from * cpu_tlbstate_shared.is_lazy whether or not to send an IPI. */ - if (WARN_ON_ONCE(prev != &init_mm && + if (IS_ENABLED(CONFIG_DEBUG_VM) && WARN_ON_ONCE(prev != &init_mm && !cpumask_test_cpu(cpu, mm_cpumask(next)))) cpumask_set_cpu(cpu, mm_cpumask(next)); |