Messages in this thread | | | Date | Thu, 2 Apr 2015 14:16:09 -0400 | From | Chris Metcalf <> | Subject | Re: [PATCH v3] watchdog: add watchdog_cpumask sysctl to assist nohz |
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On 04/02/2015 02:06 PM, Peter Zijlstra wrote: > On Thu, Apr 02, 2015 at 01:39:28PM -0400, cmetcalf@ezchip.com wrote: >> @@ -431,6 +434,10 @@ static void watchdog_enable(unsigned int cpu) >> hrtimer_init(hrtimer, CLOCK_MONOTONIC, HRTIMER_MODE_REL); >> hrtimer->function = watchdog_timer_fn; >> >> + /* Exit if the cpu is not allowed for watchdog. */ >> + if (!cpumask_test_cpu(cpu, watchdog_mask)) >> + do_exit(0); >> + > Ick, that doesn't look right for smpboot threads.
I didn't see a better way to make this happen without adding a bunch of infrastructure to the smpboot thread mechanism to use a cpumask other than for_each_online_cpu(). The exit seems benign in my testing, but I agree it's not the cleanest way to express what we're trying to do here.
Perhaps something like an optional cpumask_t pointer in struct smp_hotplug_thread, which if present specifies the cpus to run on, and otherwise we stick with cpu_online_mask?
-- Chris Metcalf, EZChip Semiconductor http://www.ezchip.com
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