From: Matthew Wilcox <willy@infradead.org>
To: Chris Goldsworthy <cgoldswo@codeaurora.org>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Minchan Kim <minchan@kernel.org>, Nitin Gupta <ngupta@vflare.org>,
Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 0/2] Increasing CMA Utilization with a GFP Flag
Date: Mon, 2 Nov 2020 14:44:49 +0000 [thread overview]
Message-ID: <20201102144449.GM27442@casper.infradead.org> (raw)
In-Reply-To: <cover.1604282969.git.cgoldswo@codeaurora.org>
On Mon, Nov 02, 2020 at 06:39:20AM -0800, Chris Goldsworthy wrote:
> The current approach to increasing CMA utilization introduced in
> commit 16867664936e ("mm,page_alloc,cma: conditionally prefer cma
> pageblocks for movable allocations") increases CMA utilization by
> redirecting MIGRATE_MOVABLE allocations to a CMA region, when
> greater than half of the free pages in a given zone are CMA pages.
> The issue in this approach is that allocations with type
> MIGRATE_MOVABLE can still succumb to pinning. To get around
> this, one approach is to re-direct allocations to the CMA areas, that
> are known not to be victims of pinning.
>
> To this end, this series brings in __GFP_CMA, which we mark with
> allocations that we know are safe to be redirected to a CMA area.
This feels backwards to me. What you're essentially saying is "Some
allocations marked with GFP_MOVABLE turn out not to be movable, so we're
going to add another GFP_REALLY_MOVABLE flag" instead of tracking down
which GFP_MOVABLE allocations aren't really movable.
next prev parent reply other threads:[~2020-11-02 14:45 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-02 14:39 [PATCH 0/2] Increasing CMA Utilization with a GFP Flag Chris Goldsworthy
2020-11-02 14:39 ` [PATCH 1/2] cma: redirect page allocation to CMA Chris Goldsworthy
2020-11-03 5:30 ` [cma] 1ea6c22c9b: page_allocation_failure:order:#,mode:#(__GFP_RECLAIMABLE),nodemask=(null) kernel test robot
2020-11-03 18:53 ` David Rientjes
2020-11-02 14:39 ` [PATCH 2/2] zram: allow zram to allocate CMA pages Chris Goldsworthy
2020-11-02 14:44 ` Matthew Wilcox [this message]
2020-11-02 17:35 ` [PATCH 0/2] Increasing CMA Utilization with a GFP Flag David Hildenbrand
2020-11-03 19:58 ` Michal Hocko
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