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    SubjectRe: [RFC][PATCH 00/32] Nohz cpusets v2 (adaptive tickless kernel)
    On Tue, 27 Mar 2012, Gilad Ben-Yossef wrote:

    > +static void vmstat_update(struct work_struct *w)
    > +{
    > + int cpu, this_cpu = smp_processor_id();
    > + int sleepy_cpu_counter = 0;
    > + static spinlock_t lock;
    > +
    > + if(spin_trylock(&lock)) {

    Trylock would cause cache bouncing between vmstat runs on various
    processors. The reason that vmstat_update exists is to avoid these cache
    bounces. Please no exclusive cacheline acquisiton by all cpus by default.

    The best method would be to assign a sacrifical lamb cpu and check if we
    are running on that cpu. That way taking a lock can be avoided.



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