On Tue, Apr 10, 2007 at 08:24:22AM +0200, Ingo Molnar wrote:
>
> * Siddha, Suresh B <[email protected]> wrote:
>
> > Align the per cpu runqueue to the cacheline boundary. This will
> > minimize the number of cachelines touched during remote wakeup.
>
> > -static DEFINE_PER_CPU(struct rq, runqueues);
> > +static DEFINE_PER_CPU(struct rq, runqueues) ____cacheline_aligned_in_smp;
>
> ouch!! Now how did _that_ slip through. The runqueues had been
> cacheline-aligned for ages. Or at least, they were supposed to be.
perhaps the per_cpu definition gave the impression of cacheline aligned too..
>
> could you see any improvement in profiles or workloads with this patch
> applied? (just curious - it's an obviously right fix)
We have seen 0.5% perf improvement on database workload on a 2 node setup.
0.5% is a very good improvement for this workload.
thanks,
suresh
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