From: Andi Kleen <ak@suse.de>
To: Andrew Morton <akpm@osdl.org>
Cc: linux-kernel@vger.kernel.org, kenneth.w.chen@intel.com
Subject: Re: Limit hash table size
Date: 06 Feb 2004 02:54:54 +0100 [thread overview]
Message-ID: <p73isilkm4x.fsf@verdi.suse.de> (raw)
In-Reply-To: <20040205155813.726041bd.akpm@osdl.org.suse.lists.linux.kernel>
Andrew Morton <akpm@osdl.org> writes:
> Ken, I remain unhappy with this patch. If a big box has 500 million
> dentries or inodes in cache (is possible), those hash chains will be more
> than 200 entries long on average. It will be very slow.
How about limiting the global size of the dcache in this case ?
I cannot imagine a workload where it would make sense to ever cache
500 million dentries. It just risks to keep the whole file system
after an updatedb in memory on a big box, which is not necessarily
good use of the memory.
Limiting the number of dentries would keep the hash chains at a
reasonable length too and somewhat bound the worst case CPU
use for cache misses and search time in cache lookups.
-Andi
next parent reply other threads:[~2004-02-06 1:57 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <B05667366EE6204181EABE9C1B1C0EB5802441@scsmsx401.sc.intel.com.suse.lists.linux.kernel>
[not found] ` <20040205155813.726041bd.akpm@osdl.org.suse.lists.linux.kernel>
2004-02-06 1:54 ` Andi Kleen [this message]
2004-02-05 2:38 ` Limit hash table size Steve Lord
2004-02-06 3:12 ` Andrew Morton
2004-02-05 4:06 ` Steve Lord
2004-02-06 4:39 ` Andi Kleen
2004-02-06 4:59 ` Andrew Morton
2004-02-06 5:34 ` Maneesh Soni
2004-02-06 3:19 ` Andi Kleen
2004-02-06 3:23 ` Nick Piggin
2004-02-06 3:34 ` Andrew Morton
2004-02-06 3:38 ` Nick Piggin
2004-02-18 12:41 ` Pavel Machek
2004-02-06 3:09 ` Andrew Morton
2004-02-06 3:18 ` Andi Kleen
2004-02-06 3:30 ` Andrew Morton
2004-02-06 4:45 ` Martin J. Bligh
2004-02-06 6:22 ` Matt Mackall
2004-02-06 20:20 ` Taneli Vähäkangas
2004-02-06 20:27 ` Andrew Morton
2004-02-06 21:46 ` Taneli Vähäkangas
2004-02-18 0:45 Chen, Kenneth W
-- strict thread matches above, loose matches on Subject: below --
2004-02-18 0:16 Chen, Kenneth W
2004-02-17 22:24 Chen, Kenneth W
2004-02-17 23:24 ` Andrew Morton
2004-02-06 6:32 Manfred Spraul
2004-02-06 0:10 Chen, Kenneth W
2004-02-06 0:23 ` Andrew Morton
2004-02-09 23:12 ` Jes Sorensen
2004-01-14 22:31 Chen, Kenneth W
2004-01-18 14:25 ` Anton Blanchard
2004-01-14 22:29 Chen, Kenneth W
2004-01-12 16:50 Manfred Spraul
2004-01-09 19:05 Chen, Kenneth W
2004-01-12 13:32 ` Anton Blanchard
2004-01-08 23:12 Chen, Kenneth W
2004-01-09 9:25 ` Andrew Morton
2004-01-09 14:25 ` Anton Blanchard
2004-02-05 23:58 ` Andrew Morton
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