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authorNicholas Piggin <npiggin@gmail.com>2017-08-09 14:41:23 +0200
committerMichael Ellerman <mpe@ellerman.id.au>2017-08-09 15:45:29 +0200
commit26c5c6e129ee725f103938262a034861ada467ae (patch)
tree7e8b4c872ddf50905a188ea738a69e0f18a75bf4 /arch
parentpowerpc/watchdog: Improve watchdog lock primitive (diff)
downloadlinux-26c5c6e129ee725f103938262a034861ada467ae.tar.xz
linux-26c5c6e129ee725f103938262a034861ada467ae.zip
powerpc/watchdog: Moderate touch_nmi_watchdog overhead
Some code can go into a tight loop calling touch_nmi_watchdog (e.g., stop_machine CPU hotplug code). This can cause contention on watchdog locks particularly if all CPUs with watchdog enabled are spinning in the loops. Avoid this storm of activity by running the watchdog timer callback from this path if we have exceeded the timer period since it was last run. Signed-off-by: Nicholas Piggin <npiggin@gmail.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Diffstat (limited to 'arch')
-rw-r--r--arch/powerpc/kernel/watchdog.c4
1 files changed, 3 insertions, 1 deletions
diff --git a/arch/powerpc/kernel/watchdog.c b/arch/powerpc/kernel/watchdog.c
index fda4d044d326..426dd34891d6 100644
--- a/arch/powerpc/kernel/watchdog.c
+++ b/arch/powerpc/kernel/watchdog.c
@@ -263,9 +263,11 @@ static void wd_timer_fn(unsigned long data)
void arch_touch_nmi_watchdog(void)
{
+ unsigned long ticks = tb_ticks_per_usec * wd_timer_period_ms * 1000;
int cpu = smp_processor_id();
- watchdog_timer_interrupt(cpu);
+ if (get_tb() - per_cpu(wd_timer_tb, cpu) >= ticks)
+ watchdog_timer_interrupt(cpu);
}
EXPORT_SYMBOL(arch_touch_nmi_watchdog);