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Mon, 15 Jun 2020 01:10:43 -0700 (PDT) Date: Mon, 15 Jun 2020 10:10:41 +0200 From: Vincent Guittot To: Xing Zhengjun Cc: Hillf Danton , kernel test robot , Ingo Molnar , Mel Gorman , Peter Zijlstra , Juri Lelli , Steven Rostedt , Valentin Schneider , Phil Auld , LKML Subject: Re: [LKP] [sched/fair] 070f5e860e: reaim.jobs_per_min -10.5% regression Message-ID: <20200615081041.GA16990@vingu-book> References: <20200319023819.GO11705@shao2-debian> <20200612110616.20264-1-hdanton@sina.com> <90f4036d-bb16-af67-8776-a2cbe67dfe7f@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <90f4036d-bb16-af67-8776-a2cbe67dfe7f@linux.intel.com> User-Agent: Mutt/1.9.4 (2018-02-28) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Xing, Le lundi 15 juin 2020 à 15:26:59 (+0800), Xing Zhengjun a écrit : > > > On 6/12/2020 7:06 PM, Hillf Danton wrote: > > > > On Fri, 12 Jun 2020 14:36:49 +0800 Xing Zhengjun wrote: ... > > --- a/kernel/sched/fair.c > > +++ b/kernel/sched/fair.c > > @@ -8215,12 +8215,8 @@ group_has_capacity(unsigned int imbalanc > > if (sgs->sum_nr_running < sgs->group_weight) > > return true; > > - if ((sgs->group_capacity * imbalance_pct) < > > - (sgs->group_runnable * 100)) > > - return false; > > - > > - if ((sgs->group_capacity * 100) > > > - (sgs->group_util * imbalance_pct)) > > + if ((sgs->group_capacity * 100) > (sgs->group_util * imbalance_pct) && > > + (sgs->group_capacity * 100) > (sgs->group_runnable * imbalance_pct)) > > return true; > > return false; > > @@ -8240,12 +8236,8 @@ group_is_overloaded(unsigned int imbalan > > if (sgs->sum_nr_running <= sgs->group_weight) > > return false; > > - if ((sgs->group_capacity * 100) < > > - (sgs->group_util * imbalance_pct)) > > - return true; > > - > > - if ((sgs->group_capacity * imbalance_pct) < > > - (sgs->group_runnable * 100)) > > + if ((sgs->group_capacity * 100) < (sgs->group_util * imbalance_pct) || > > + (sgs->group_capacity * 100) < (sgs->group_runnable * imbalance_pct)) > > return true; > > return false; > > > > I apply the patch based on v5.7, the regression still existed. Thanks for the test. I don't know if it's relevant or not but the results seem a bit better with the patch and I'd like to check that it's only a matter of threshold to fix the problem. Could you try the patch below which is quite aggressive but will help to confirm this ? diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 28be1c984a42..3c51d557547b 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -8322,10 +8322,13 @@ static inline int sg_imbalanced(struct sched_group *group) static inline bool group_has_capacity(unsigned int imbalance_pct, struct sg_lb_stats *sgs) { + unsigned long imb; + if (sgs->sum_nr_running < sgs->group_weight) return true; - if ((sgs->group_capacity * imbalance_pct) < + imb = sgs->sum_nr_running * 100; + if ((sgs->group_capacity * imb) < (sgs->group_runnable * 100)) return false; @@ -8347,6 +8350,8 @@ group_has_capacity(unsigned int imbalance_pct, struct sg_lb_stats *sgs) static inline bool group_is_overloaded(unsigned int imbalance_pct, struct sg_lb_stats *sgs) { + unsigned long imb; + if (sgs->sum_nr_running <= sgs->group_weight) return false; @@ -8354,7 +8359,8 @@ group_is_overloaded(unsigned int imbalance_pct, struct sg_lb_stats *sgs) (sgs->group_util * imbalance_pct)) return true; - if ((sgs->group_capacity * imbalance_pct) < + imb = sgs->sum_nr_running * 100; + if ((sgs->group_capacity * imb) < (sgs->group_runnable * 100)) return true; > > ========================================================================================= > tbox_group/testcase/rootfs/kconfig/compiler/runtime/nr_task/debug-setup/test/cpufreq_governor/ucode: > > lkp-ivb-d04/reaim/debian-x86_64-20191114.cgz/x86_64-rhel-7.6/gcc-7/300s/100%/test/five_sec/performance/0x21 > > commit: > 9f68395333ad7f5bfe2f83473fed363d4229f11c > 070f5e860ee2bf588c99ef7b4c202451faa48236 > v5.7 > 6b33257768b8dd3982054885ea310871be2cfe0b (Hillf's patch) > > 9f68395333ad7f5b 070f5e860ee2bf588c99ef7b4c2 v5.7 > 6b33257768b8dd3982054885ea3 > ---------------- --------------------------- --------------------------- > --------------------------- > %stddev %change %stddev %change %stddev %change > %stddev > \ | \ | \ > | \ > 0.69 -10.3% 0.62 -9.1% 0.62 > -10.1% 0.62 reaim.child_systime > 0.62 -1.0% 0.61 +0.5% 0.62 > +0.3% 0.62 reaim.child_utime > 66870 -10.0% 60187 -7.6% 61787 > -8.3% 61305 reaim.jobs_per_min > 16717 -10.0% 15046 -7.6% 15446 > -8.3% 15326 reaim.jobs_per_min_child > 97.84 -1.1% 96.75 -0.4% 97.43 > -0.5% 97.37 reaim.jti > 72000 -10.8% 64216 -8.3% 66000 > -8.3% 66000 reaim.max_jobs_per_min > 0.36 +10.6% 0.40 +7.8% 0.39 > +9.4% 0.39 reaim.parent_time > 1.58 ± 2% +71.0% 2.70 ± 2% +26.9% 2.01 ± 2% > +33.2% 2.11 reaim.std_dev_percent > 0.00 ± 5% +110.4% 0.01 ± 3% +48.8% 0.01 ± 7% > +65.3% 0.01 ± 3% reaim.std_dev_time > 50800 -2.4% 49600 -1.6% 50000 > -1.8% 49866 reaim.workload > > > > -- > Zhengjun Xing