Messages in this thread | | | Date | Mon, 26 Jan 2015 12:35:00 -0600 (CST) | From | Christoph Lameter <> | Subject | Re: [PATCH v2] mm: vmscan: fix the page state calculation in too_many_isolated |
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On Mon, 26 Jan 2015, Michal Hocko wrote:
> > Please do not run the vmstat_updates concurrently. They update shared > > cachelines and therefore can cause bouncing cachelines if run concurrently > > on multiple cpus. > > Would you preffer to call smp_call_function_single on each CPU > which needs an update? That would make vmstat_shepherd slower but that > is not a big deal, is it?
Run it from the timer interrupt as usual from a work request? Those are staggered.
> Anyway I am wondering whether the cache line bouncing between > vmstat_update instances is a big deal in the real life. Updating shared > counters whould bounce with many CPUs but this is an operation which is > not done often. Also all the CPUs would have update the same counters > all the time and I am not sure this happens that often. Do you have a > load where this would be measurable?
Concurrent page faults update lots of counters concurrently. But will those trigger the smp_call_function?
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