linux-kernel - Re: [PATCH v4 13/13] x86/folio_zero

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Message-ID: <871prjzgxx.fsf@oracle.com>
Date: Mon, 16 Jun 2025 11:20:42 -0700
From: Ankur Arora <ankur.a.arora@...cle.com>
To: Peter Zijlstra <peterz@...radead.org>
Cc: Dave Hansen <dave.hansen@...el.com>,
        Ankur Arora
 <ankur.a.arora@...cle.com>, linux-kernel@...r.kernel.org,
        linux-mm@...ck.org, x86@...nel.org, akpm@...ux-foundation.org,
        bp@...en8.de, dave.hansen@...ux.intel.com, hpa@...or.com,
        mingo@...hat.com, mjguzik@...il.com, luto@...nel.org, acme@...nel.org,
        namhyung@...nel.org, tglx@...utronix.de, willy@...radead.org,
        jon.grimm@....com, bharata@....com, raghavendra.kt@....com,
        boris.ostrovsky@...cle.com, konrad.wilk@...cle.com
Subject: Re: [PATCH v4 13/13] x86/folio_zero_user: Add multi-page clearing


Peter Zijlstra <peterz@...radead.org> writes:

> On Mon, Jun 16, 2025 at 07:44:13AM -0700, Dave Hansen wrote:
>
>> To me, that's deserving of an ARCH_HAS_FOO bit that we can set on the
>> x86 side that then cajoles the core mm/ code to use the fancy new
>> clear_pages_resched() implementation.
>
> Note that we should only set this bit with either full or lazy
> preemption selected. Haven't checked the patch-set to see if that
> constraint is already taken care of.

It is. I check for preempt_model_preemptible() and limit voluntary models
to chunk sizes of 8MB.

--
ankur