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From: Hugh Dickins <hughd@google.com>
To: Matthew Wilcox <willy@infradead.org>
Cc: Hugh Dickins <hughd@google.com>,
	Johannes Weiner <hannes@cmpxchg.org>,
	 Andrew Morton <akpm@linux-foundation.org>,
	 Song Liu <songliubraving@fb.com>,
	 "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
	 linux-kernel@vger.kernel.org, linux-mm@kvack.org
Subject: Re: [PATCH] mm,thp: stop leaking unreleased file pages
Date: Wed, 3 Jun 2020 15:19:42 -0700 (PDT)	[thread overview]
Message-ID: <alpine.LSU.2.11.2006031506500.32284@eggly.anvils> (raw)
In-Reply-To: <20200603215122.GR19604@bombadil.infradead.org>

On Wed, 3 Jun 2020, Matthew Wilcox wrote:
> On Wed, May 27, 2020 at 02:28:10PM -0700, Hugh Dickins wrote:
> > Saying "source inspection" reminds me: there is another funny in there,
> > but I don't think it matters very much in practice, and might need
> > rather a lot of testing to justify any particular patch: where
> > page_cache_sync_readahead() asks for PAGE_SIZE pages!
> > 
> > "end - index" seems a more reasonable number to me: but then we
> > might find that reading ahead into the next huge extent had actually
> > been a useful optimization (and those readahead functions impose
> > their own caps, so PAGE_SIZE shouldn't work out too outrageously).
> 
> That readahead was only added in 99cb0dbd47a15d395bf3faa78dc122bc5efe3fc0
> so it probably hasn't really been performance tested yet.

I can well imagine that an entirely new body of code, exercised
in the background by khugepaged, will not be a leading candidate for
performance comparisons - rightly so; but arguing that by the commit
being in the tree for only eight months seems... odd :)

Hugh


      reply	other threads:[~2020-06-03 22:20 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-05-24  1:50 Hugh Dickins
2020-05-25  0:05 ` Song Liu
2020-05-25  4:32 ` Kirill A. Shutemov
2020-05-26 16:01 ` Johannes Weiner
2020-05-27 21:28   ` Hugh Dickins
2020-05-28  8:51     ` Naresh Kamboju
2020-06-03 21:51     ` Matthew Wilcox
2020-06-03 22:19       ` Hugh Dickins [this message]

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