From: H. Peter Anvin <hpa@zytor.com>
Date: Thu, 14 Apr 2005 05:36:52 GMT
Subject: Re: Yet another base64 patch
Message-ID: <425E0174.4080404@zytor.com>
In-Reply-To: <20050414022413.GB18655@64m.dyndns.org>

Christopher Li wrote:
> On Wed, Apr 13, 2005 at 09:19:48PM -0700, H. Peter Anvin wrote:
> 
>>Checking out the total kernel tree (time checkout-cache -a into an empty 
>>directory):
>>
>>	Cache cold	Cache hot
>>stock	3:46.95		19.95
>>base64	5:56.20		23.74
>>flat	2:44.13		15.68
> 
>>It seems that the flat format, at least on ext3 with dircache, is 
>>actually a major performance win, and that the second level loses quite 
>>a bit.
> 
> That is not surprising due to the directory index in ext3. Htree is pretty
> good at random access and the hashed file name distribute evenly, that is
> the best case for htree. 
> 

Right, so by not trying to do the filesystem's job for it we actually 
come out ahead.

	-hpa