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SubjectRE: [PATCH v3] sched/topology: fix the issue groups don't span domain->span for NUMA diameter > 2
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> -----Original Message-----
> From: Meelis Roos [mailto:mroos@linux.ee]
> Sent: Wednesday, February 10, 2021 1:40 AM
> To: Song Bao Hua (Barry Song) <song.bao.hua@hisilicon.com>;
> valentin.schneider@arm.com; vincent.guittot@linaro.org; mgorman@suse.de;
> mingo@kernel.org; peterz@infradead.org; dietmar.eggemann@arm.com;
> morten.rasmussen@arm.com; linux-kernel@vger.kernel.org
> Cc: linuxarm@openeuler.org; xuwei (O) <xuwei5@huawei.com>; Liguozhu (Kenneth)
> <liguozhu@hisilicon.com>; tiantao (H) <tiantao6@hisilicon.com>; wanghuiqiang
> <wanghuiqiang@huawei.com>; Zengtao (B) <prime.zeng@hisilicon.com>; Jonathan
> Cameron <jonathan.cameron@huawei.com>; guodong.xu@linaro.org
> Subject: Re: [PATCH v3] sched/topology: fix the issue groups don't span
> domain->span for NUMA diameter > 2
>
> I did a rudimentary benchmark on the same 8-node Sun Fire X4600-M2, on top of
> todays 5.11.0-rc7-00002-ge0756cfc7d7c.
>
> The test: building clean kernel with make -j64 after make clean and drop_caches.
>
> While running clean kernel / 3 tries):
>
> real 2m38.574s
> user 46m18.387s
> sys 6m8.724s
>
> real 2m37.647s
> user 46m34.171s
> sys 6m11.993s
>
> real 2m37.832s
> user 46m34.910s
> sys 6m12.013s
>
>
> While running patched kernel:
>
> real 2m40.072s
> user 46m22.610s
> sys 6m6.658s
>
>
> for real time, seems to be 1.5s-2s slower out of 160s (noise?) User and system
> time are slightly less, on the other hand, so seems good to me.

I ran the same test on the machine with the below topology:
numactl --hardware
available: 4 nodes (0-3)
node 0 cpus: 0-31
node 0 size: 64144 MB
node 0 free: 62356 MB
node 1 cpus: 32-63
node 1 size: 64509 MB
node 1 free: 62996 MB
node 2 cpus: 64-95
node 2 size: 64509 MB
node 2 free: 63020 MB
node 3 cpus: 96-127
node 3 size: 63991 MB
node 3 free: 62647 MB
node distances:
node 0 1 2 3
0: 10 12 20 22
1: 12 10 22 24
2: 20 22 10 12
3: 22 24 12 10

Basically the influence to kernel build is noise by
the commands I ran a couple of rounds:

make clean
echo 3 > /proc/sys/vm/drop_caches
make Image -j100

w/ patch: w/o patch:

real 1m17.644s real 1m19.510s
user 32m12.074s user 32m14.133s
sys 4m35.827s sys 4m38.198s

real 1m15.855s real 1m17.303s
user 32m7.700s user 32m14.128s
sys 4m35.868s sys 4m40.094s

real 1m18.918s real 1m19.583s
user 32m13.352s user 32m13.205s
sys 4m40.161s sys 4m40.696s

real 1m20.329s real 1m17.819s
user 32m7.255s user 32m11.753s
sys 4m36.706s sys 4m41.371s

real 1m17.773s real 1m16.763s
user 32m19.912s user 32m15.607s
sys 4m36.989s sys 4m41.297s

real 1m14.943s real 1m18.551s
user 32m14.549s user 32m18.521s
sys 4m38.670s sys 4m41.392s

real 1m16.439s real 1m18.154s
user 32m12.864s user 32m14.540s
sys 4m39.424s sys 4m40.364s

our team guys who used the 3-hops-fix patch to run unixbench
reported some data of unixbench score as below(3 rounds):

w/o patch: w/ patch:
1228.6 1254.9
1231.4 1265.7
1226.1 1266.1

One interesting thing is that if we change the kernel to
disallow the below BALANCING flags for the last hop,
sd->flags &= ~(SD_BALANCE_EXEC |
SD_BALANCE_FORK |
SD_WAKE_AFFINE);

We are seeing further increase of unixbench. So sounds like
those balancing shouldn't go that far. But it is a different
topic.

>
> --
> Meelis Roos <mroos@linux.ee>

Thanks
Barry

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