Re: [PATCH 00/18 v2] Improving latency of short slice tasks

[Vincent Guittot]

On Thu, 8 Oct 2026 at 21:13, Kayra Cizmeci <kayracizmeci@xxxxxxxxx> wrote:
>
> Hi All,
>
> I wanted to ran some tests for this patch series. I couldn't really
> apply it without some issues, but I think I managed to apply
> it cleanly this time... Tho I may have been doing something wrong.
> Please let me know if so.
>
> base: 4a3b51aab6e25244d97936aa65e6d5425adf98e1 (on tip/sched/core)
>
> Command Used Each Run:
>
> hackbench -g 4 -l 100000 > /dev/null & sudo chrt -o -T 300000 0 ~/rt-tests/cyclictest --policy=other -t 1 -i 1000 -D 20 -q -m; wait
>
> Environment:
>
> Zen 3 with 8 Cores and 16 Threads. And Fedora.
>
> THE RESULTS (COOKED):
>
> On Base in 5 runs, average values are: Min: 3.8, Act: 5.8, Avg: 8.8 and
> Max: 2511.6 (I need tea.)
>
> On Base + Patches in 5 runs, average values bla bla you get it:
> Min 4, Act: 5.8, Avg: 7.2 and Max: 1781.6
>
> Or, in the shape of art made with love and passion:
>
>  +------BASE-----+--PATCHED--+
>  | MIN   3.8     |    4      |
>  | ACT   5.8     |   5.8     |
>  | AVG   8.8     |   7.2     |
>  | MAX  2511.6   |  1781.6   |
>  +--------------+------------+

Thanks for testing

>
> Hmhp... Hope I'm not missing something. I need water. Bah.
>
> Tested-by: Kayra Cizmeci <kayracizmeci@xxxxxxxxx>
>
> Dancing donkey chases a car while shouting "Linux is the best, my dancing is the coolest. Cry."
>
> Thanks,
> Kayra
>
>
>
> I'll add other not too important things below, these are pretty raw.
> But if you wanna have a look you can.
>
>
> THE RESULTS (RAW):
>
> BASE 7.3.0-rc1+ #2:
>
> RUN 1:
> [1] 1950
> # /dev/cpu_dma_latency set to 0us
> T: 0 ( 2115) P: 0 I:1000 C:  19990 Min:      4 Act:    6 Avg:    8 Max:    1885
> [1]+  Done                       hackbench -g 4 -l 100000 > /dev/null
>
> RUN 2:
> [1] 2132
> # /dev/cpu_dma_latency set to 0us
> T: 0 ( 2297) P: 0 I:1000 C:  19990 Min:      4 Act:    6 Avg:    9 Max:    2695
> [1]+  Done                       hackbench -g 4 -l 100000 > /dev/null
>
> linuxfucks@micro-softly:~$ (Opsies. Who's hostname is this? It's so cool. Wow. 'linuxfucks')
>
> RUN 3:
> [1] 2307
> # /dev/cpu_dma_latency set to 0us
> T: 0 ( 2472) P: 0 I:1000 C:  19988 Min:      4 Act:    5 Avg:    8 Max:    3246
> [1]+  Done                       hackbench -g 4 -l 100000 > /dev/null
>
> RUN 4:
> [1] 2493
> # /dev/cpu_dma_latency set to 0us
> T: 0 ( 2658) P: 0 I:1000 C:  19995 Min:      3 Act:    6 Avg:    9 Max:    1991
> [1]+  Done                       hackbench -g 4 -l 100000 > /dev/null
>
> RUN 5:
> [1] 2671
> # /dev/cpu_dma_latency set to 0us
> T: 0 ( 2836) P: 0 I:1000 C:  19992 Min:      4 Act:    6 Avg:   10 Max:    2741
> [1]+  Done                       hackbench -g 4 -l 100000 > /dev/null
>
> BASE + PATCHES 7.3.0-rc1+ #3:
>
> RUN 1:
> [1] 1490
> # /dev/cpu_dma_latency set to 0us
> T: 0 ( 1657) P: 0 I:1000 C:  19993 Min:      4 Act:    5 Avg:    7 Max:    3091
> [1]+  Done                       hackbench -g 4 -l 100000 > /dev/null
>
> RUN 2:
> [1] 1671
> # /dev/cpu_dma_latency set to 0us
> T: 0 ( 1836) P: 0 I:1000 C:  19999 Min:      4 Act:    6 Avg:    7 Max:    1529
> [1]+  Done                       hackbench -g 4 -l 100000 > /dev/null
>
> RUN 3:
> [1] 1848
> # /dev/cpu_dma_latency set to 0us
> T: 0 ( 2013) P: 0 I:1000 C:  19998 Min:      4 Act:    6 Avg:    7 Max:    1455
> [1]+  Done                       hackbench -g 4 -l 100000 > /dev/null
>
> RUN 4:
> [1] 2023
> # /dev/cpu_dma_latency set to 0us
> T: 0 ( 2188) P: 0 I:1000 C:  19995 Min:      4 Act:    6 Avg:    7 Max:    1524
> [1]+  Done                       hackbench -g 4 -l 100000 > /dev/null
>
> RUN 5:
> [1] 2200
> # /dev/cpu_dma_latency set to 0us
> T: 0 ( 2365) P: 0 I:1000 C:  19989 Min:      4 Act:    6 Avg:    8 Max:    1309
> [1]+  Done                       hackbench -g 4 -l 100000 > /dev/null
>
>
>