From: Patrick Bellasi <patrick.bellasi@arm.com> To: Aaron Lu <aaron.lu@intel.com> Cc: "Ye, Xiaolong" <xiaolong.ye@intel.com>, Joel Fernandes <joelaf@google.com>, Juri Lelli <juri.lelli@redhat.com>, Todd Kjos <tkjos@android.com>, Stephen Rothwell <sfr@canb.auug.org.au>, Peter Zijlstra <peterz@infradead.org>, Paul Turner <pjt@google.com>, "Wysocki, Rafael J" <rafael.j.wysocki@intel.com>, Morten Rasmussen <morten.rasmussen@arm.com>, Dietmar Eggemann <dietmar.eggemann@arm.com>, Steve Muckle <smuckle@google.com>, "lkp@01.org" <lkp@01.org>, Viresh Kumar <viresh.kumar@linaro.org>, Chris Redpath <chris.redpath@arm.com>, Thomas Gleixner <tglx@linutronix.de>, Linus Torvalds <torvalds@linux-foundation.org>, Ingo Molnar <mingo@kernel.org>, LKML <linux-kernel@vger.kernel.org> Subject: Re: [LKP] [lkp-robot] [sched/fair] d519329f72: unixbench.score -9.9% regression Date: Thu, 25 Oct 2018 10:31:00 +0100 [thread overview] Message-ID: <20181025093100.GB13236@e110439-lin> (raw) In-Reply-To: <20181025085629.GA18146@intel.com> On 25-Oct 16:56, Aaron Lu wrote: > On Wed, Oct 24, 2018 at 06:01:37PM +0100, Patrick Bellasi wrote: > > On 24-Oct 14:41, Aaron Lu wrote: > > > On Mon, Apr 02, 2018 at 11:20:00AM +0800, Ye, Xiaolong wrote: > > > > > > > > Greeting, > > > > > > > > FYI, we noticed a -9.9% regression of unixbench.score due to commit: > > > > > > > > > > > > commit: d519329f72a6f36bc4f2b85452640cfe583b4f81 ("sched/fair: Update util_est only on util_avg updates") > > > > https://git.kernel.org/cgit/linux/kernel/git/next/linux-next.git master > > > > > > > > in testcase: unixbench > > > > on test machine: 8 threads Intel(R) Core(TM) i7 CPU 870 @ 2.93GHz with 6G memory > > > > with following parameters: > > > > > > > > runtime: 300s > > > > nr_task: 100% > > > > test: execl > > > > > > > > test-description: UnixBench is the original BYTE UNIX benchmark suite aims to test performance of Unix-like system. > > > > test-url: https://github.com/kdlucas/byte-unixbench > > > > Hi Aaron, > > > > > I tested this workload on different machines with this commit > > > d519329f72a6f36bc4f2b85452 and its parent a07630b8b2c16f82, I also > > > tested with v4.19-rc8 to see if the regression is gone - > > > the performance drop is there with v4.19-rc8 and with different > > > machines so I assume this regression is not solved yet. > > > > > > Here are detailed data: > > > > > > cmdline used to run this workload: > > > ./Run execl -c $nr_cpu -i 30 > > > > I had a better look into this issue and found that something like this > > could be the cure for the execl throughput regression: > > Good news, yes they are! Great. > > ---8<--- > > diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c > > index 908c9cdae2f0..c34d41b542fc 100644 > > --- a/kernel/sched/fair.c > > +++ b/kernel/sched/fair.c > > @@ -6258,8 +6258,17 @@ static unsigned long cpu_util_wake(int cpu, struct task_struct *p) > > * covered by the following code when estimated utilization is > > * enabled. > > */ > > - if (sched_feat(UTIL_EST)) > > - util = max(util, READ_ONCE(cfs_rq->avg.util_est.enqueued)); > > + if (sched_feat(UTIL_EST)) { > > + unsigned int estimated = > > + READ_ONCE(cfs_rq->avg.util_est.enqueued); > > + > > + if (unlikely(current == p)) { > > + estimated -= min_t(unsigned int, estimated, > > + (_task_util_est(p) | UTIL_AVG_UNCHANGED)); > > + } > > + > > + util = max(util, estimated); > > + } > > > > /* > > * Utilization (estimated) can exceed the CPU capacity, thus let's > > ---8<--- > > > > I'll test this better on a machine on my side and send out a proper > > patch by tomorrow. > > > > > Please let me know if you need other information, thanks. > > > > Would be nice if you can test the above on your side too. > > > > commit cbcb74a95c5af32f9127a102feca323139ba2c49 is the commit I made > from your diff and it restored performance for the two desktops. the > result on the skylake server isn't quite stable so I think the > performance gap is due to noise. > > lkp-ivb-d04: > cbcb74a95c5af32f9127a102feca323139ba2c49/avg.json: "unixbench.score": 2946.0, > d519329f72a6f36bc4f2b85452640cfe583b4f81/avg.json: "unixbench.score": 2669.5333333333333, > a07630b8b2c16f82fd5b71d890079f4dd7599c1d/avg.json: "unixbench.score": 2924.3333333333335, > > lkp-hsw-d01: > cbcb74a95c5af32f9127a102feca323139ba2c49/avg.json: "unixbench.score": 7013.533333333333, > d519329f72a6f36bc4f2b85452640cfe583b4f81/avg.json: "unixbench.score": 6421.233333333333, > a07630b8b2c16f82fd5b71d890079f4dd7599c1d/avg.json: "unixbench.score": 7090.400000000001, > > lkp-skl-2sp2: > cbcb74a95c5af32f9127a102feca323139ba2c49/avg.json: "unixbench.score": 9347.02, > d519329f72a6f36bc4f2b85452640cfe583b4f81/avg.json: "unixbench.score": 9362.76, > a07630b8b2c16f82fd5b71d890079f4dd7599c1d/avg.json: "unixbench.score": 9520.86, I've measured a ~15% speedup with the patch in wrt v4.19.0 on a 40 CPUs Intel(R) Xeon(R) CPU E5-2690 v2 @ 3.00GHz. ################################################################################ ### Mainline (v4.19.0): Benchmark Run: Wed Oct 24 2018 16:13:34 - 16:19:04 40 CPUs in system; running 40 parallel copies of tests Execl Throughput 48136.5 lps (29.9 s, 7 samples) System Benchmarks Partial Index BASELINE RESULT INDEX Execl Throughput 43.0 48136.5 11194.5 ======== System Benchmarks Index Score (Partial Only) 11194.5 ################################################################################ ### Mainline (v4.19.0) + patch: Benchmark Run: Wed Oct 24 2018 16:29:56 - 16:35:26 40 CPUs in system; running 40 parallel copies of tests Execl Throughput 55373.6 lps (29.9 s, 7 samples) System Benchmarks Partial Index BASELINE RESULT INDEX Execl Throughput 43.0 55373.6 12877.6 ======== System Benchmarks Index Score (Partial Only) 12877.6 ################################################################################ Thanks again reporting and testing on your side, I'll post soon a proper patch. Cheers Patrick -- #include <best/regards.h> Patrick Bellasi
prev parent reply other threads:[~2018-10-25 9:31 UTC|newest] Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top 2018-04-02 3:20 kernel test robot 2018-04-03 11:43 ` Patrick Bellasi 2018-04-04 6:14 ` Ye Xiaolong 2018-10-24 6:41 ` [LKP] " Aaron Lu 2018-10-24 17:01 ` Patrick Bellasi 2018-10-25 8:56 ` Aaron Lu 2018-10-25 9:31 ` Patrick Bellasi [this message]
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