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Date:      Fri, 26 Aug 2005 09:12:45 +0100
From:      David Malone <dwmalone@maths.tcd.ie>
To:        Marian Hettwer <MH@kernel32.de>
Cc:        freebsd-current@freebsd.org, Mike Tancsa <mike@sentex.net>
Subject:   Re: filesystem performance with lots of small files
Message-ID:  <20050826081245.GA83206@walton.maths.tcd.ie>
In-Reply-To: <430E3743.3030108@kernel32.de>
References:  <430E06AA.2000907@kernel32.de> <6.2.3.4.0.20050825135916.07a19ac8@64.7.153.2> <430E3743.3030108@kernel32.de>

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On Thu, Aug 25, 2005 at 11:25:23PM +0200, Marian Hettwer wrote:
> I didn't changed anything from the defaults... it looks like that:
> mhettwer@submaster-test$ sysctl vfs.ufs.dirhash_maxmem
> vfs.ufs.dirhash_maxmem: 2097152
> mhettwer@submaster-test$ sysctl vfs.ufs.dirhash_mem
> vfs.ufs.dirhash_mem: 368622
> 
> By the way, the copy job of my small files finished, so here we go with 
> some small facts :)
> mhettwer@submaster-test$ sudo time find /usr/tmp/ | wc -l
>       133.81 real         2.01 user         3.95 sys
>  2904696

(Sorry - I missed the start of this thread.)

With dirhash it is how many files/directories you have in one
directory that is important. Subdirectories don't count. One way
to get a rough estimate of how big you should make vfs.ufs.dirhash_maxmem
is do to "ls -ld /usr/tmp" and see how many bytes the directory
takes. The number of bytes shown is probably a reasonable estimate
of what you should set vfs.ufs.dirhash_maxmem to.

	David.



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