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Message-ID: <676c08bc-3714-4824-8743-cf98b45a5ab9@rasmusvillemoes.dk>
Date:   Wed, 25 Oct 2023 17:34:04 +0200
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Subject: Re: [POC][RFC][PATCH] sched: Extended Scheduler Time Slice
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To:     Steven Rostedt <rostedt@goodmis.org>,
        LKML <linux-kernel@vger.kernel.org>
Cc:     Thomas Gleixner <tglx@linutronix.de>,
        Peter Zijlstra <peterz@infradead.org>,
        Ankur Arora <ankur.a.arora@oracle.com>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        linux-mm@kvack.org, x86@kernel.org, akpm@linux-foundation.org,
        luto@kernel.org, bp@alien8.de, dave.hansen@linux.intel.com,
        hpa@zytor.com, mingo@redhat.com, juri.lelli@redhat.com,
        vincent.guittot@linaro.org, willy@infradead.org, mgorman@suse.de,
        jon.grimm@amd.com, bharata@amd.com, raghavendra.kt@amd.com,
        boris.ostrovsky@oracle.com, konrad.wilk@oracle.com,
        jgross@suse.com, andrew.cooper3@citrix.com,
        Joel Fernandes <joel@joelfernandes.org>,
        Youssef Esmat <youssefesmat@chromium.org>,
        Vineeth Pillai <vineethrp@google.com>,
        Suleiman Souhlal <suleiman@google.com>,
        Ingo Molnar <mingo@kernel.org>,
        Daniel Bristot de Oliveira <bristot@kernel.org>
References: <20231025054219.1acaa3dd@gandalf.local.home>
From:   Rasmus Villemoes <linux@rasmusvillemoes.dk>
In-Reply-To: <20231025054219.1acaa3dd@gandalf.local.home>
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On 25/10/2023 11.42, Steven Rostedt wrote:

> So, bit 1 is for user space to tell the kernel "please extend me", and bit
> two is for the kernel to tell user space "OK, I extended you, but call
> sched_yield() when done".
I'm not qualified to have an opinion on this. But this sounds quite
similar to
https://lore.kernel.org/lkml/1395767870-28053-1-git-send-email-khalid.aziz@oracle.com/
.

  "A thread sends the scheduler this request by setting a flag in
a memory location it has shared with the kernel.  Kernel uses bytes in
the same memory location to let the thread know when its request for
amnesty from preemption has been granted. Thread should yield the
processor at the end of its critical section if it was granted amnesty
to play nice with other threads."

Rasmus