linux-kernel - Re: [PATCH v2] mm: Optimise put_pages

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Message-ID: <YWBS6iJr/4RJ+hNE@casper.infradead.org>
Date:   Fri, 8 Oct 2021 15:17:14 +0100
From:   Matthew Wilcox <willy@...radead.org>
To:     Andrew Morton <akpm@...ux-foundation.org>
Cc:     Mel Gorman <mgorman@...hsingularity.net>, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org, anthony.yznaga@...cle.com
Subject: Re: [PATCH v2] mm: Optimise put_pages_list()

On Thu, Oct 07, 2021 at 04:35:54PM -0700, Andrew Morton wrote:
> On Thu, 7 Oct 2021 21:55:21 +0100 Matthew Wilcox <willy@...radead.org> wrote:
> > My first response is an appeal to authority -- release_pages() does
> > this same thing.  Only it takes an array, constructs a list and passes
> > that to put_unref_page_list().  So if that's slower (and lists _are_
> > slower than arrays), we should have a put_unref_page_array().
> 
> And put_unref_page_list() does two passes across the list!
> 
> <quietly sobs>
> 
> Here is my beautiful release_pages(), as disrtibuted in linux-2.5.33:

I think that looks much better!

> I guess the current version is some commentary on the aging process?

I blame the guy who sent cc59850ef940 to Linus back in 2011 ...

I think Anthony was going to look into this and perhaps revert us to
a pagevec_free() interface.