From: Mel Gorman <mgorman@techsingularity.net>
To: Rong Qianfeng <rongqianfeng@vivo.com>
Cc: vbabka@suse.cz, Andrew Morton <akpm@linux-foundation.org>,
Mike Rapoport <rppt@kernel.org>,
"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
Zi Yan <ziy@nvidia.com>,
Baolin Wang <baolin.wang@linux.alibaba.com>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
opensource.kernel@vivo.com
Subject: Re: [PATCH] mm: Skip the reserved bootmem for compaction
Date: Wed, 4 Sep 2024 12:13:56 +0100 [thread overview]
Message-ID: <5fmd2poyeas2pomho2io5zgmqd26vnxd77czmlhqn5tapy4fv4@5tdcqamzgyj5> (raw)
In-Reply-To: <20240902122445.11805-1-rongqianfeng@vivo.com>
On Mon, Sep 02, 2024 at 08:24:43PM +0800, Rong Qianfeng wrote:
> Reserved pages are basically non-lru pages. This kind of memory can't be
> used as migration sources and targets, skip it can bring some performance
> benefits.
>
> Because some drivers may also use PG_reserved, we just set PB_migrate_skip
> for those clustered reserved bootmem during memory initialization.
>
> Signed-off-by: Rong Qianfeng <rongqianfeng@vivo.com>
I'm not convinced the savings due to skipping a few pages during the scan
would justify the additional code. There would have to be a large number
of reserved pages scattered throughout the zone to make a difference and
even that situation would be a big surprise. I'm not even sure this can be
explicitly tested unless you artifically create reserved pages throughout the
zone, which would not be convincing, or know if a driver that exhibits such
behaviour in which case my first question is -- what is that driver doing?!?
--
Mel Gorman
SUSE Labs
next prev parent reply other threads:[~2024-09-04 11:14 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-09-02 12:24 Rong Qianfeng
2024-09-02 13:45 ` David Hildenbrand
2024-09-03 7:14 ` Rong Qianfeng
2024-09-03 9:56 ` David Hildenbrand
2024-09-04 11:13 ` Mel Gorman [this message]
2024-09-04 11:59 ` Rong Qianfeng
2024-09-04 15:38 ` Mike Rapoport
2024-09-05 3:10 ` Rong Qianfeng
2024-09-04 14:54 ` kernel test robot
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