linux-kernel - Re: [PATCH v2 7/9] sched: define TIF_ALLOW

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Date:   Tue, 12 Sep 2023 13:33:56 +0100
From:   Matthew Wilcox <willy@...radead.org>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     Ankur Arora <ankur.a.arora@...cle.com>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        linux-kernel@...r.kernel.org, linux-mm@...ck.org, x86@...nel.org,
        akpm@...ux-foundation.org, luto@...nel.org, bp@...en8.de,
        dave.hansen@...ux.intel.com, hpa@...or.com, mingo@...hat.com,
        juri.lelli@...hat.com, vincent.guittot@...aro.org, mgorman@...e.de,
        rostedt@...dmis.org, tglx@...utronix.de, jon.grimm@....com,
        bharata@....com, raghavendra.kt@....com,
        boris.ostrovsky@...cle.com, konrad.wilk@...cle.com,
        jgross@...e.com, andrew.cooper3@...rix.com
Subject: Re: [PATCH v2 7/9] sched: define TIF_ALLOW_RESCHED

On Tue, Sep 12, 2023 at 10:26:06AM +0200, Peter Zijlstra wrote:
> > How expensive would be always having PREEMPT_COUNT=y?
> 
> Effectively I think that is true today. At the very least Debian and
> SuSE (I can't find a RHEL .config in a hurry but I would think they too)
> ship with PREEMPT_DYNAMIC=y.

$ grep PREEMPT uek-rpm/ol9/config-x86_64
# CONFIG_PREEMPT_NONE is not set
CONFIG_PREEMPT_VOLUNTARY=y
# CONFIG_PREEMPT is not set
CONFIG_HAVE_PREEMPT_DYNAMIC=y
CONFIG_PREEMPT_NOTIFIERS=y
CONFIG_DRM_I915_PREEMPT_TIMEOUT=640
# CONFIG_PREEMPTIRQ_DELAY_TEST is not set

$ grep PREEMPT uek-rpm/ol9/config-aarch64
# CONFIG_PREEMPT_NONE is not set
CONFIG_PREEMPT_VOLUNTARY=y
# CONFIG_PREEMPT is not set
CONFIG_PREEMPT_NOTIFIERS=y
# CONFIG_PREEMPTIRQ_DELAY_TEST is not set