> -----Original Message----- > From: Vincent Guittot [mailto:vincent.guittot@xxxxxxxxxx] > Sent: Thursday, December 3, 2020 10:39 PM > To: Song Bao Hua (Barry Song) <song.bao.hua@xxxxxxxxxxxxx> > Cc: Valentin Schneider <valentin.schneider@xxxxxxx>; Catalin Marinas > <catalin.marinas@xxxxxxx>; Will Deacon <will@xxxxxxxxxx>; Rafael J. Wysocki > <rjw@xxxxxxxxxxxxx>; Cc: Len Brown <lenb@xxxxxxxxxx>; > gregkh@xxxxxxxxxxxxxxxxxxx; Jonathan Cameron <jonathan.cameron@xxxxxxxxxx>; > Ingo Molnar <mingo@xxxxxxxxxx>; Peter Zijlstra <peterz@xxxxxxxxxxxxx>; Juri > Lelli <juri.lelli@xxxxxxxxxx>; Dietmar Eggemann <dietmar.eggemann@xxxxxxx>; > Steven Rostedt <rostedt@xxxxxxxxxxx>; Ben Segall <bsegall@xxxxxxxxxx>; Mel > Gorman <mgorman@xxxxxxx>; Mark Rutland <mark.rutland@xxxxxxx>; LAK > <linux-arm-kernel@xxxxxxxxxxxxxxxxxxx>; linux-kernel > <linux-kernel@xxxxxxxxxxxxxxx>; ACPI Devel Maling List > <linux-acpi@xxxxxxxxxxxxxxx>; Linuxarm <linuxarm@xxxxxxxxxx>; xuwei (O) > <xuwei5@xxxxxxxxxx>; Zengtao (B) <prime.zeng@xxxxxxxxxxxxx> > Subject: Re: [RFC PATCH v2 2/2] scheduler: add scheduler level for clusters > > On Thu, 3 Dec 2020 at 10:11, Song Bao Hua (Barry Song) > <song.bao.hua@xxxxxxxxxxxxx> wrote: > > > > > > > > > -----Original Message----- > > > From: Vincent Guittot [mailto:vincent.guittot@xxxxxxxxxx] > > > Sent: Thursday, December 3, 2020 10:04 PM > > > To: Song Bao Hua (Barry Song) <song.bao.hua@xxxxxxxxxxxxx> > > > Cc: Valentin Schneider <valentin.schneider@xxxxxxx>; Catalin Marinas > > > <catalin.marinas@xxxxxxx>; Will Deacon <will@xxxxxxxxxx>; Rafael J. Wysocki > > > <rjw@xxxxxxxxxxxxx>; Cc: Len Brown <lenb@xxxxxxxxxx>; > > > gregkh@xxxxxxxxxxxxxxxxxxx; Jonathan Cameron > <jonathan.cameron@xxxxxxxxxx>; > > > Ingo Molnar <mingo@xxxxxxxxxx>; Peter Zijlstra <peterz@xxxxxxxxxxxxx>; Juri > > > Lelli <juri.lelli@xxxxxxxxxx>; Dietmar Eggemann > <dietmar.eggemann@xxxxxxx>; > > > Steven Rostedt <rostedt@xxxxxxxxxxx>; Ben Segall <bsegall@xxxxxxxxxx>; Mel > > > Gorman <mgorman@xxxxxxx>; Mark Rutland <mark.rutland@xxxxxxx>; LAK > > > <linux-arm-kernel@xxxxxxxxxxxxxxxxxxx>; linux-kernel > > > <linux-kernel@xxxxxxxxxxxxxxx>; ACPI Devel Maling List > > > <linux-acpi@xxxxxxxxxxxxxxx>; Linuxarm <linuxarm@xxxxxxxxxx>; xuwei (O) > > > <xuwei5@xxxxxxxxxx>; Zengtao (B) <prime.zeng@xxxxxxxxxxxxx> > > > Subject: Re: [RFC PATCH v2 2/2] scheduler: add scheduler level for clusters > > > > > > On Wed, 2 Dec 2020 at 21:58, Song Bao Hua (Barry Song) > > > <song.bao.hua@xxxxxxxxxxxxx> wrote: > > > > > > > > > > > > > > Sorry. Please ignore this. I added some printk here while testing > > > > > one numa. Will update you the data in another email. > > > > > > > > Re-tested in one NUMA node(cpu0-cpu23): > > > > > > > > g=1 > > > > Running in threaded mode with 1 groups using 40 file descriptors > > > > Each sender will pass 100000 messages of 100 bytes > > > > w/o: 7.689 7.485 7.485 7.458 7.524 7.539 7.738 7.693 7.568 7.674=7.5853 > > > > w/ : 7.516 7.941 7.374 7.963 7.881 7.910 7.420 7.556 7.695 7.441=7.6697 > > > > w/ but dropped select_idle_cluster: > > > > 7.752 7.739 7.739 7.571 7.545 7.685 7.407 7.580 7.605 7.487=7.611 > > > > > > > > g=2 > > > > Running in threaded mode with 2 groups using 40 file descriptors > > > > Each sender will pass 100000 messages of 100 bytes > > > > w/o: 10.127 10.119 10.070 10.196 10.057 10.111 10.045 10.164 10.162 > > > > 9.955=10.1006 > > > > w/ : 9.694 9.654 9.612 9.649 9.686 9.734 9.607 9.842 9.690 9.710=9.6878 > > > > w/ but dropped select_idle_cluster: > > > > 9.877 10.069 9.951 9.918 9.947 9.790 9.906 9.820 9.863 9.906=9.9047 > > > > > > > > g=3 > > > > Running in threaded mode with 3 groups using 40 file descriptors > > > > Each sender will pass 100000 messages of 100 bytes > > > > w/o: 15.885 15.254 15.932 15.647 16.120 15.878 15.857 15.759 15.674 > > > > 15.721=15.7727 > > > > w/ : 14.974 14.657 13.969 14.985 14.728 15.665 15.191 14.995 14.946 > > > > 14.895=14.9005 > > > > w/ but dropped select_idle_cluster: > > > > 15.405 15.177 15.373 15.187 15.450 15.540 15.278 15.628 15.228 > > > 15.325=15.3591 > > > > > > > > g=4 > > > > Running in threaded mode with 4 groups using 40 file descriptors > > > > Each sender will pass 100000 messages of 100 bytes > > > > w/o: 20.014 21.025 21.119 21.235 19.767 20.971 20.962 20.914 21.090 > > > 21.090=20.8187 > > > > w/ : 20.331 20.608 20.338 20.445 20.456 20.146 20.693 20.797 21.381 > > > 20.452=20.5647 > > > > w/ but dropped select_idle_cluster: > > > > 19.814 20.126 20.229 20.350 20.750 20.404 19.957 19.888 20.226 > > > 20.562=20.2306 > > > > > > > > > > I assume that you have run this on v5.9 as previous tests. > > > > Yep > > > > > The results don't show any real benefit of select_idle_cluster() > > > inside a node whereas this is where we could expect most of the > > > benefit. We have to understand why we have such an impact on numa > > > tests only. > > > > There is a 4-5.5% increase while g=2 and g=3. > > my point was with vs without select_idle_cluster() but still having a > cluster domain level > In this case, the diff is -0.8% for g=1 +2.2% for g=2, +3% for g=3 and > -1.7% for g=4 > > > > > Regarding the huge increase in NUMA case, at the first beginning, I suspect > > we have wrong llc domain. For example, if cpu0's llc domain span > > cpu0-cpu47, then select_idle_cpu() is running in wrong range while > > it should run in cpu0-cpu23. > > > > But after printing the llc domain's span, I find it is completely right. > > Cpu0's llc span: cpu0-cpu23 > > Cpu24's llc span: cpu24-cpu47 > > Have you checked that the cluster mask was also correct ? > > > > > Maybe I need more trace data to figure out if select_idle_cpu() is running > > correctly. For example, maybe I can figure out if it is always returning -1, > > or it returns -1 very often? > > yes, could be interesting to check how often select_idle_cpu return -1 > > > > > Or do you have any idea? > > tracking migration across nod could help to understand too I set a bootargs mem=4G to do swapping test before working on cluster scheduler issue. but I forgot to remove the parameter. The huge increase on across-numa case can only be reproduced while i use this mem=4G cmdline which means numa1 has no memory. After removing the limitation, I can't reproduce the huge increase for two NUMAs any more. Guess select_idle_cluster() somehow workaround an scheduler issue for numa without memory. > > Vincent > > > > Thanks Barry
