From: Christoph Hellwig <hch@infradead.org>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Davidlohr Bueso <davidlohr@hp.com>,
Andrew Morton <akpm@linux-foundation.org>,
Hugh Dickins <hughd@google.com>,
Michel Lespinasse <walken@google.com>,
Ingo Molnar <mingo@kernel.org>, Mel Gorman <mgorman@suse.de>,
Rik van Riel <riel@redhat.com>, Guan Xuetao <gxt@mprc.pku.edu.cn>,
"Chandramouleeswaran, Aswin" <aswin@hp.com>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
linux-mm <linux-mm@kvack.org>, Dave Chinner <dchinner@redhat.com>
Subject: Re: [PATCH] mm: cache largest vma
Date: Sun, 3 Nov 2013 23:03:28 -0800 [thread overview]
Message-ID: <20131104070328.GA17995@infradead.org> (raw)
In-Reply-To: <CA+55aFwrtOaFtwGc6xyZH6-1j3f--AG1JS-iZM8-pZPnwRHBow@mail.gmail.com>
On Sun, Nov 03, 2013 at 10:51:27AM -0800, Linus Torvalds wrote:
> Ugh. This patch makes me angry. It looks way too ad-hoc.
>
> I can well imagine that our current one-entry cache is crap and could
> be improved, but this looks too random. Different code for the
> CONFIG_MMU case? Same name, but for non-MMU it's a single entry, for
> MMU it's an array? And the whole "largest" just looks odd. Plus why do
> you set LAST_USED if you also set LARGEST?
>
> Did you try just a two- or four-entry pseudo-LRU instead, with a
> per-thread index for "last hit"? Or even possibly a small fixed-size
> hash table (say "idx = (add >> 10) & 3" or something)?
Btw, Dave Chiner has recently implemented a simple look aside cache for
the buffer cache, which also uses a rbtree. Might beworth into making
that into a generic library and use it here:
http://thread.gmane.org/gmane.comp.file-systems.xfs.general/56220
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prev parent reply other threads:[~2013-11-04 7:03 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-11-01 20:17 [PATCH] mm: cache largest vma Davidlohr Bueso
2013-11-01 20:38 ` KOSAKI Motohiro
2013-11-01 21:11 ` Davidlohr Bueso
2013-11-03 9:46 ` Ingo Molnar
2013-11-03 23:57 ` KOSAKI Motohiro
2013-11-04 4:22 ` Davidlohr Bueso
2013-11-01 21:23 ` Rik van Riel
2013-11-03 10:12 ` Ingo Molnar
2013-11-04 4:20 ` Davidlohr Bueso
2013-11-04 4:48 ` converting unicore32 to gate_vma as done for arm (was Re: [PATCH] mm: cache largest vma) Al Viro
2013-11-05 2:49 ` 管雪涛
2013-11-11 7:25 ` converting unicore32 to gate_vma as done for arm (was " Al Viro
2013-11-04 7:00 ` [PATCH] mm: cache largest vma Ingo Molnar
2013-11-04 7:05 ` Ingo Molnar
2013-11-04 14:20 ` Frederic Weisbecker
2013-11-04 17:52 ` Ingo Molnar
2013-11-04 18:10 ` Frederic Weisbecker
2013-11-05 8:24 ` Ingo Molnar
2013-11-05 14:27 ` Jiri Olsa
2013-11-06 6:01 ` Ingo Molnar
2013-11-06 14:03 ` Konstantin Khlebnikov
2013-11-03 18:51 ` Linus Torvalds
2013-11-04 4:04 ` Davidlohr Bueso
2013-11-04 7:36 ` Ingo Molnar
2013-11-04 14:56 ` Michel Lespinasse
2013-11-11 4:12 ` Davidlohr Bueso
2013-11-11 7:43 ` Michel Lespinasse
2013-11-11 12:04 ` Ingo Molnar
2013-11-11 20:47 ` Davidlohr Bueso
2013-11-13 17:08 ` Davidlohr Bueso
2013-11-13 17:59 ` Ingo Molnar
2013-11-13 18:16 ` Peter Zijlstra
2013-11-11 12:01 ` Ingo Molnar
2013-11-11 18:24 ` Davidlohr Bueso
2013-11-11 20:47 ` Ingo Molnar
2013-11-11 20:59 ` Davidlohr Bueso
2013-11-11 21:09 ` Ingo Molnar
2013-11-04 7:03 ` Christoph Hellwig [this message]
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