Re: [RFC PATCH v7 11/23] sched/fair: core wide cfs task priority comparison

From: chris hyser
Date: Wed Sep 16 2020 - 18:21:01 EST

On 9/16/20 8:57 AM, Li, Aubrey wrote:
Here are the uperf results of the various patchsets. Note, that disabling smt is better for these tests and that that presumably reflects the overall overhead of core scheduling which went from bad to really bad. The primary focus in this email is to start to understand what happened within core sched itself.

patchset          smt=on/cs=off  smt=off    smt=on/cs=on
v5-v5.6.y      :    1.78Gb/s     1.57Gb/s     1.07Gb/s
pre-v6-v5.6.y  :    1.75Gb/s     1.55Gb/s    822.16Mb/s
v6-5.7         :    1.87Gs/s     1.56Gb/s    561.6Mb/s
v6-5.7-hotplug :    1.75Gb/s     1.58Gb/s    438.21Mb/s
v7             :    1.80Gb/s     1.61Gb/s    440.44Mb/s

I haven't had a chance to play with v7, but I got something different.

branch smt=on/cs=on
coresched/v5-v5.6.y 1.09Gb/s
coresched/v6-v5.7.y 1.05Gb/s

I attached my kernel config in case you want to make a comparison, or you
can send yours, I'll try to see I can replicate your result.

I will give this config a try. One of the reports forwarded to me about the drop in uperf perf was an email from you I believe mentioning a 50% perf drop between v5 and v6?? I was actually setting out to duplicate your results. :-)