Messages in this thread | | | Subject | Re: [PATCH 2/3] sched: introduce per-cpu var next_cpu to track search limit | From | Subhra Mazumdar <> | Date | Tue, 24 Apr 2018 15:39:40 -0700 |
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On 04/24/2018 05:47 AM, Peter Zijlstra wrote: > On Mon, Apr 23, 2018 at 05:41:15PM -0700, subhra mazumdar wrote: >> @@ -17,6 +17,7 @@ >> #include <trace/events/sched.h> >> >> DEFINE_PER_CPU_SHARED_ALIGNED(struct rq, runqueues); >> +DEFINE_PER_CPU_SHARED_ALIGNED(int, next_cpu); >> >> #if defined(CONFIG_SCHED_DEBUG) && defined(HAVE_JUMP_LABEL) >> /* >> @@ -6018,6 +6019,7 @@ void __init sched_init(void) >> struct rq *rq; >> >> rq = cpu_rq(i); >> + per_cpu(next_cpu, i) = -1; > If you leave it uninitialized it'll be 0, and we can avoid that extra > branch in the next patch, no? 0 can be a valid cpu id. I wanted to distinguish the first time. The branch predictor will be fully trained so will not have any cost.
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