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From: Joonsoo Kim <js1304@gmail.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Linux Memory Management List <linux-mm@kvack.org>,
	LKML <linux-kernel@vger.kernel.org>,
	Michal Hocko <mhocko@kernel.org>,
	Vlastimil Babka <vbabka@suse.cz>,
	"Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com>,
	Mel Gorman <mgorman@techsingularity.net>,
	kernel-team@lge.com, Joonsoo Kim <iamjoonsoo.kim@lge.com>
Subject: Re: [PATCH v2 for v5.9] mm/page_alloc: handle a missing case for memalloc_nocma_{save/restore} APIs
Date: Tue, 29 Sep 2020 15:46:02 +0900	[thread overview]
Message-ID: <CAAmzW4NPv+mu5P9=jHf0XgcrPjbCKJZR1hQkUkPvcTHb-0q50g@mail.gmail.com> (raw)
In-Reply-To: <20200928215055.02ff9b3ff5e0c392b2403411@linux-foundation.org>

2020년 9월 29일 (화) 오후 1:50, Andrew Morton <akpm@linux-foundation.org>님이 작성:
>
> On Tue, 29 Sep 2020 10:28:05 +0900 Joonsoo Kim <js1304@gmail.com> wrote:
>
> > > What about manually emptying the pcplists beforehand?
> >
> > It also increases the probability. schedule() or interrupt after emptying but
> > before the allocation could invalidate the effect.
>
> Keep local interrupts disabled across the pcp drain and the allocation
> attempt.

As said before, it's an allocation context API and actual allocation
happens later.
Doing such things there is not an easy job.

> > > Or byassing the pcplists for this caller and calling __rmqueue() directly?
> >
> > What this patch does is this one.
>
> I meant via a different function rather than by adding overhead to the
> existing commonly-used function.

Got it. One idea could be disabling/enabling pcp list on these APIs but
it's overhead would not be appropriate on these APIs. I don't have
another idea that doesn't touch the allocation path.

Thanks.

  reply	other threads:[~2020-09-29  6:46 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-09-28  8:50 [PATCH v2 for v5.9] mm/page_alloc: handle a missing case for memalloc_nocma_{save/restore} APIs js1304
2020-09-28 23:52 ` Andrew Morton
2020-09-29  1:28   ` Joonsoo Kim
2020-09-29  4:50     ` Andrew Morton
2020-09-29  6:46       ` Joonsoo Kim [this message]
2020-09-29  8:08 ` Michal Hocko
2020-09-29  8:38   ` Joonsoo Kim
2020-09-29  9:53     ` Michal Hocko
2020-09-29  8:13 ` Vlastimil Babka

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