Re: [PATCH 1/5] sched/fair: ignore SIS_UTIL when has idle core

[Abel Wu]

Hi Chen, thanks for your testing!

On 8/10/22 9:50 PM, Chen Yu Wrote:
> On Tue, Jul 12, 2022 at 4:45 PM Abel Wu <wuyun.abel@xxxxxxxxxxxxx> wrote:
> > When SIS_UTIL is enabled, SIS domain scan will be skipped if
> > the LLC is overloaded. Since the overloaded status is checked
> > in the load balancing at LLC level, the interval is llc_size
> > miliseconds. The duration might be long enough to affect the
> > overall system throughput if idle cores are out of reach in
> > SIS domain scan.
> >
> > Signed-off-by: Abel Wu <wuyun.abel@xxxxxxxxxxxxx>
> > ---
> Tested schbench and netperf on latest 5.19 vanilla, it seems that there
> is latency performance improvement when the load is low in schbench,
> and no performance difference on netperf.
>
>   ./report.py -b 5.19.0+ -c 5.19.0-skip-sis-util+ -t schbench
>
> schbench
> ========
> case            load    baseline(std%) compare%( std%)
> normal          mthread-1 1.00 (  0.00) +7.69 (  0.00)
> normal          mthread-2 1.00 (  0.00) +13.24 (  0.00)
> normal          mthread-4 1.00 (  0.00) -5.88 (  0.00)
> normal          mthread-8 1.00 (  0.00) -0.25 (  0.00)
>
>
> ./report.py -b 5.19.0+ -c 5.19.0-skip-sis-util+ -t netperf
> netperf
> =======
> case            load    baseline(std%) compare%( std%)
> TCP_RR          thread-28 1.00 (  0.62) +0.15 (  0.55)
> TCP_RR          thread-56 1.00 (  0.42) -0.26 (  0.40)
> TCP_RR          thread-84 1.00 (  0.29) +0.39 (  0.29)
> TCP_RR          thread-112 1.00 (  0.22) +0.44 (  0.23)
> TCP_RR          thread-140 1.00 (  0.17) +0.33 (  0.18)
> TCP_RR          thread-168 1.00 (  0.17) +0.19 (  0.16)
> TCP_RR          thread-196 1.00 ( 13.65) -0.62 ( 14.83)
> TCP_RR          thread-224 1.00 (  9.80) -0.65 (  9.67)
> UDP_RR          thread-28 1.00 (  0.89) +0.92 (  0.81)
> UDP_RR          thread-56 1.00 (  0.78) +0.38 (  0.73)
> UDP_RR          thread-84 1.00 ( 14.03) +0.78 ( 16.85)
> UDP_RR          thread-112 1.00 ( 12.26) -0.42 ( 11.95)
> UDP_RR          thread-140 1.00 (  9.86) -0.89 (  6.93)
> UDP_RR          thread-168 1.00 ( 11.62) -0.82 (  8.80)
> UDP_RR          thread-196 1.00 ( 19.47) +0.42 ( 16.50)
> UDP_RR          thread-224 1.00 ( 18.68) +0.72 ( 18.50)
>
>
> Tested-by: Chen Yu <yu.c.chen@xxxxxxxxx>