Re: [PATCH 1/2] sched/fair: Couple wakee flips with heavy wakers

From: Mike Galbraith
Date: Sat Oct 30 2021 - 00:12:49 EST


On Sat, 2021-10-30 at 05:11 +0200, Mike Galbraith wrote:
>
> I profiled it with a perf that sums delay (local mod I find useful)...

Here are those numbers for completeness. As you can see, patchlet was
fairly meaningless to the desktop load. In fact, even though the wake
affine logic essentially favors the compute load over the heavily
threaded but light desktop load, I noticed zero difference with or
without that being allowed, nor did perf record any noteworthy latency
events, just more wait as load was kinda sorta de-treaded by being
stacked up.

box = i7-4790 quad+smt
desktop vs massive_intr 8 9999 (8 x 8ms run/1ms sleep, for 9999 secs.. effectively forever)
perf sched record -a -- su mikeg -c 'firefox https://www.youtube.com/watch?v=aqz-KE-bpKQ'& sleep 300 && killall perf firefox
runtime runtime sum delay sum delay sum delay switches desktop
patch/features total util massive_intr util total massive_intr desktop total/massive util
virgin/stock 2267347.921 ms 94.4% 1932675.152 ms 80.5% 158611.016 ms 133309.938 ms 25301.078 ms 594780/441157 13.9%
virgin/-wa_weight 2236871.408 ms 93.2% 1881464.401 ms 78.3% 255785.391 ms 243958.616 ms 11826.775 ms 1525470/1424083 14.8%
-1.34% -1.2% -2.2% -13.474 s +0.9%
wake_wide/stock 2254335.961 ms 93.9% 1917834.157 ms 79.9% 164766.194 ms 141974.540 ms 22791.654 ms 720711/599064 14.0%