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From: Mel Gorman <mgorman@techsingularity.net>
To: "Matthew Wilcox (Oracle)" <willy@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [RFC] mm: Optimise put_pages_list()
Date: Mon, 4 Oct 2021 10:10:37 +0100	[thread overview]
Message-ID: <20211004091037.GM3959@techsingularity.net> (raw)
In-Reply-To: <20210930163258.3114404-1-willy@infradead.org>

On Thu, Sep 30, 2021 at 05:32:58PM +0100, Matthew Wilcox (Oracle) wrote:
> Instead of calling put_page() one page at a time, pop pages off
> the list if there are other refcounts and pass the remainder
> to free_unref_page_list().  This should be a speed improvement,
> but I have no measurements to support that.  It's also not very
> widely used today, so I can't say I've really tested it.  I'm only
> bothering with this patch because I'd like the IOMMU code to use it
> https://lore.kernel.org/lkml/20210930162043.3111119-1-willy@infradead.org/
> 
> Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>

I see your motivation but you need to check that all users of
put_pages_list (current and future) handle destroy_compound_page properly
or handle it within put_pages_list. For example, the release_pages()
user of free_unref_page_list calls __put_compound_page directly before
freeing. put_pages_list as it stands will call dstroy_compound_page but
free_unref_page_list does not destroy compound pages in free_pages_prepare

-- 
Mel Gorman
SUSE Labs

  reply	other threads:[~2021-10-04  9:10 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-30 16:32 [RFC] mm: Optimise put_pages_list() Matthew Wilcox (Oracle)
2021-10-04  9:10 ` Mel Gorman [this message]
2021-10-04 12:49   ` Matthew Wilcox
2021-10-04 14:29     ` Mel Gorman

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