From: Zhaoyang Huang <huangzhaoyang@gmail.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: "zhaoyang.huang" <zhaoyang.huang@unisoc.com>,
Roman Gushchin <guro@fb.com>, Minchan Kim <minchan@kernel.org>,
Roman Gushchin <roman.gushchin@linux.dev>,
Joonsoo Kim <iamjoonsoo.kim@lge.com>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
ke.wang@unisoc.com
Subject: Re: [PATCHv5] mm: optimization on page allocation when CMA enabled
Date: Sun, 8 Oct 2023 15:54:40 +0800 [thread overview]
Message-ID: <CAGWkznHqQHMN1QXz7os7AQTYdzc3+LEq+z2bWOzLbiseV=560A@mail.gmail.com> (raw)
In-Reply-To: <20231006141750.5423083520f74bc0746fd249@linux-foundation.org>
On Sat, Oct 7, 2023 at 5:17 AM Andrew Morton <akpm@linux-foundation.org> wrote:
>
> On Thu, 11 May 2023 13:22:30 +0800 "zhaoyang.huang" <zhaoyang.huang@unisoc.com> wrote:
>
> > From: Zhaoyang Huang <zhaoyang.huang@unisoc.com>
> >
> > Let us look at the timeline of scenarios below with WMARK_LOW=25MB WMARK_MIN=5MB
> > (managed pages 1.9GB). We can find that CMA begin to be used until 'C' under the
> > method of 'fixed 2 times of free cma over free pages' which could have the
> > scenario 'A' and 'B' into a fault state, that is, free UNMOVABLE & RECLAIMABLE
> > pages is lower than corresponding watermark without reclaiming which should be
> > deemed as against current memory policy. This commit try to solve this by
> > checking zone_watermark_ok again with removing CMA pages which could lead to a
> > proper time point of CMA's utilization.
> >
> > -- Free_pages
> > |
> > |
> > -- WMARK_LOW
> > |
> > -- Free_CMA
> > |
> > |
> > --
> >
> > Free_CMA/Free_pages(MB) A(12/30) --> B(12/25) --> C(12/20)
> > fixed 1/2 ratio N N Y
> > this commit Y Y Y
> >
>
> Roman previously asked
>
> : Also I'm a bit concerned about potential performance implications.
> : Would be great to provide some benchmarks or some data. Probably it's
> : ok because of we have pcp caches on top, but I'm not 100% sure.
>
> Are you able to perform such testing and tell us the result?
I have applied this patch in a v5.4 based ANDROID system and got no
regression problem. Actually, this commit is aimed to have
alloc_pages(GFP_USER) use CMA instead of stealing U&R(could lead to
GFP_KERNEL fail) only when zone's free pages and free cma are around
WATERMARK_LOW/MIN which would NOT affect most scenarios.
>
> Thanks.
>
next prev parent reply other threads:[~2023-10-08 7:54 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-05-11 5:22 zhaoyang.huang
2023-10-06 21:17 ` Andrew Morton
2023-10-08 7:54 ` Zhaoyang Huang [this message]
2023-10-10 0:14 ` Andrew Morton
2023-10-10 1:31 ` Roman Gushchin
2023-10-10 1:42 ` Zhaoyang Huang
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