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 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..

  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