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Date: Sun, 27 Mar 2005 20:48:44 -0800
From: Julian Elischer <julian@elischer.org>
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To: Poul-Henning Kamp <phk@phk.freebsd.dk>, freebsd-fs@freebsd.org
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Subject: Re: UFS Subdirectory limit.
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Poul-Henning Kamp wrote:
> In message <20050326213048.GA33703@VARK.MIT.EDU>, David Schultz writes:
> 
>>On Fri, Mar 25, 2005, Scott Long wrote:
>>
>>>David Schultz wrote:
>>>
>>>>On Sat, Mar 26, 2005, David Malone wrote:
>>>>
>>>>
>>>>>There was a discussion on comp.unix.bsd.freebsd.misc about two weeks
>>>>>ago, where someone had an application that used about 150K
>>>>>subdirectories of a single directory. They wanted to move this
>>>>>application to FreeBSD, but discovered that UFS is limited to 32K
>>>>>subdirectories, because UFS's link count field is a signed 16 bit
>>>>>quantity. Rewriting the application wasn't an option for them.
> 
> 
> Has anybody here wondered how much searching a 150K directory would
> suck performance wise ?
> 
> I realize that with dir-hashing and vfs-cache it is not as bad as it
> used to be, but I still think it will be unpleasant performance wise.

We have a reason (*) to have 300000 entries in a directory..
once the dirhash cache size was made big enough, performance was acceptable.


(*) (we didn't want to  but had to for "a while until it's fixed")

>