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? -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
