Re: [PATCH v8 2/2] sched/fair: Introduce SIS_CURRENT to wake up short task on current CPU

[Mike Galbraith]

On Mon, 2023-05-01 at 17:32 +0200, Mike Galbraith wrote:
> On Mon, 2023-05-01 at 15:48 +0200, Peter Zijlstra wrote:
> >
> > Throughput  646.55 MB/sec   2 clients   2 procs  max_latency=0.104
> > ms
> > Throughput 1361.06 MB/sec   5 clients   5 procs  max_latency=0.100
> > ms
> > Throughput 1889.82 MB/sec  10 clients  10 procs  max_latency=0.154
> > ms
> > Throughput 2406.57 MB/sec  20 clients  20 procs  max_latency=3.667
> > ms
> > Throughput 2318.00 MB/sec  40 clients  40 procs  max_latency=0.390
> > ms
> > Throughput 2384.85 MB/sec  80 clients  80 procs  max_latency=1.371
> > ms
> >
> >
> > So what's going on here? I don't see anything exciting happening at
> > the
> > 40 mark. At the same time, I can't seem to reproduce Mike's latency
> > pile
> > up either :/
>
> Are you running tbench in the GUI so the per second output stimulates
> assorted goo?  I'm using KDE fwtw.
>
> Caught this from my raspberry pi, tbench placement looks lovely, the
> llvmpipe thingies otoh..

erm, without 14 feet of whitespace.

  PID USER      PR  NI    VIRT    RES    SHR S  %CPU  %MEM     TIME+ P COMMAND
19109 git       20   0   23468   1920   1664 R 52.65 0.012   3:59.64 4 tbench
19110 git       20   0   23468   1664   1536 R 52.65 0.010   4:00.03 3 tbench
19104 git       20   0   23468   1664   1536 R 52.32 0.010   4:00.15 1 tbench
19105 git       20   0   23468   1664   1536 R 52.32 0.010   4:00.16 0 tbench
19108 git       20   0   23468   1792   1664 R 52.32 0.011   4:00.12 7 tbench
19111 git       20   0   23468   1792   1664 R 51.99 0.011   4:00.33 5 tbench
19106 git       20   0   23468   1664   1536 R 51.66 0.010   3:59.40 6 tbench
19107 git       20   0   23468   1664   1536 R 51.32 0.010   3:59.72 2 tbench
19114 git       20   0    6748    896    768 R 46.69 0.006   3:32.77 6 tbench_srv
19116 git       20   0    6748    768    768 S 46.69 0.005   3:32.17 7 tbench_srv
19118 git       20   0    6748    768    768 S 46.69 0.005   3:31.70 3 tbench_srv
19117 git       20   0    6748    768    768 S 46.36 0.005   3:32.99 4 tbench_srv
19112 git       20   0    6748    768    768 S 46.03 0.005   3:32.51 1 tbench_srv
19113 git       20   0    6748    768    768 R 46.03 0.005   3:32.48 0 tbench_srv
19119 git       20   0    6748    768    768 S 46.03 0.005   3:31.93 5 tbench_srv
19115 git       20   0    6748    768    768 R 45.70 0.005   3:32.70 2 tbench_srv
 2492 root      20   0  392608 110044  70276 S 1.987 0.682   8:06.86 3 X
 2860 root      20   0 2557284 183260 138568 S 0.662 1.135   2:06.38 6 llvmpipe-1
 2861 root      20   0 2557284 183260 138568 S 0.662 1.135   2:06.44 6 llvmpipe-2
 2863 root      20   0 2557284 183260 138568 S 0.662 1.135   2:04.94 6 llvmpipe-4
 2864 root      20   0 2557284 183260 138568 S 0.662 1.135   2:04.72 6 llvmpipe-5
 2866 root      20   0 2557284 183260 138568 S 0.662 1.135   2:04.49 6 llvmpipe-7
19562 root      20   0   26192   4876   3596 R 0.662 0.030   0:00.43 5 top
 2837 root      20   0 2557284 183260 138568 S 0.331 1.135   1:51.39 5 kwin_x11
 2859 root      20   0 2557284 183260 138568 S 0.331 1.135   2:07.56 6 llvmpipe-0
 2862 root      20   0 2557284 183260 138568 S 0.331 1.135   2:05.97 6 llvmpipe-3
 2865 root      20   0 2557284 183260 138568 S 0.331 1.135   2:03.84 6 llvmpipe-6
 2966 root      20   0 3829152 323000 174992 S 0.331 2.001   0:12.71 4 llvmpipe-7
 2998 root      20   0 1126332 116960  78032 S 0.331 0.725   0:25.58 3 konsole