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Date:   Wed, 25 Oct 2023 11:12:47 -0400
From:   Steven Rostedt <>
To:     LKML <>
Cc:     Thomas Gleixner <>,
        Peter Zijlstra <>,
        Ankur Arora <>,
        Linus Torvalds <>,,,,,,,,,,,,,,,,,,,,
        Joel Fernandes <>,
        Youssef Esmat <>,
        Vineeth Pillai <>,
        Suleiman Souhlal <>,
        Ingo Molnar <>,
        Daniel Bristot de Oliveira <>,
        Mathieu Desnoyers <>
Subject: Re: [POC][RFC][PATCH] sched: Extended Scheduler Time Slice

On Wed, 25 Oct 2023 05:42:19 -0400
Steven Rostedt <> wrote:

> I ran a traceeval tool on it (still work in progress, but I can post when
> it's done), and with the following trace, and the writes to trace-marker
> (tracefs_printf)
>  trace-cmd record -e sched_switch ./extend-sched
> It showed that without the extend, each task was preempted while holding
> the lock around 200 times. With the extend, only one task was ever
> preempted while holding the lock, and it only happened once!

And looking at the trace, it was because it was preempted by an RT task.

    extend-sched-3349  [007]  3309.320747: print:                tracing_mark_write: Have lock!
    extend-sched-3349  [007]  3309.320751: sched_switch:         extend-sched:3349 [120] R ==> migration/7:68 [0]
     migration/7-68    [007]  3309.320754: sched_switch:         migration/7:68 [0] S ==> extend-sched:3349 [120]
    extend-sched-3349  [007]  3309.320756: print:                tracing_mark_write: released lock!

So we know that part of the code works. ;-)

-- Steve

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