Messages in this thread Patch in this message | | | Subject | Re: [PATCH 1/5] sched: limit cpu search in select_idle_cpu | From | Subhra Mazumdar <> | Date | Tue, 12 Jun 2018 15:12:50 -0700 |
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On 06/12/2018 01:33 PM, kbuild test robot wrote: > Hi subhra, > > Thank you for the patch! Perhaps something to improve: > > [auto build test WARNING on tip/sched/core] > [also build test WARNING on v4.17 next-20180612] > [if your patch is applied to the wrong git tree, please drop us a note to help improve the system] > > url: https://github.com/0day-ci/linux/commits/subhra-mazumdar/Improve-scheduler-scalability-for-fast-path/20180613-015158 > config: i386-randconfig-x070-201823 (attached as .config) > compiler: gcc-7 (Debian 7.3.0-16) 7.3.0 > reproduce: > # save the attached .config to linux build tree > make ARCH=i386 > > All warnings (new ones prefixed by >>): > > kernel/sched/fair.c: In function 'select_idle_cpu': >>> kernel/sched/fair.c:6396:3: warning: ISO C90 forbids mixed declarations and code [-Wdeclaration-after-statement] > u64 span_avg = sd->span_weight * avg_idle; > ^~~ > > <snip>
I fixed this patch, please try the following
---8<---
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index e497c05..7243146 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -6372,7 +6372,7 @@ static int select_idle_cpu(struct task_struct *p, struct sched_domain *sd, int t u64 avg_cost, avg_idle; u64 time, cost; s64 delta; - int cpu, nr = INT_MAX; + int cpu, limit, floor, nr = INT_MAX;
this_sd = rcu_dereference(*this_cpu_ptr(&sd_llc)); if (!this_sd) @@ -6390,10 +6390,17 @@ static int select_idle_cpu(struct task_struct *p, struct sched_domain *sd, int t
if (sched_feat(SIS_PROP)) { u64 span_avg = sd->span_weight * avg_idle; - if (span_avg > 4*avg_cost) + floor = cpumask_weight(topology_sibling_cpumask(target)); + if (floor < 2) + floor = 2; + limit = 2*floor; + if (span_avg > floor*avg_cost) { nr = div_u64(span_avg, avg_cost); - else - nr = 4; + if (nr > limit) + nr = limit; + } else { + nr = floor; + } }
time = local_clock();
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