From: Ted Ts'o <tytso@mit.edu>
To: Eric Sandeen <sandeen@redhat.com>
Cc: Andreas Dilger <adilger@dilger.ca>,
ext4 development <linux-ext4@vger.kernel.org>,
Wei Yongjun <yjwei@cn.fujitsu.com>
Subject: Re: Any qualms about reverting 3d0518f4, ext4: New rec_len encoding for very large blocksizes ?
Date: Tue, 3 Aug 2010 19:12:19 -0400 [thread overview]
Message-ID: <20100803231219.GH9453@thunk.org> (raw)
In-Reply-To: <4C589CF2.9030406@redhat.com>
On Tue, Aug 03, 2010 at 05:49:22PM -0500, Eric Sandeen wrote:
>
> As far as I know, reverting it won't break 64kb dir blocks...?
I seem to recall there was some confusion about what was the correct
way of recording a rec_len of 64k --- 0 or 65535. So after reverting
the patch, we need to make sure we didn't end up breaking
compatibility with (a) existing file systems and (b) what older
versions of mke2fs may have generated.
> >> (this does 200 iterations) and got this for the file creations:
> >>
> >> ext4 stock: Average = 21206.8 files/s
> >> ext4 patched: Average = 22822.1 files/s
> >>
> >> This is a 7.6% improvement...
Wow. I assume that was because actually ending up burning enough CPU
time that it slowed bonnie's performance? I'm not sure how how
realistic is a benchmark that is simply creating vast numbers of small
files in a tight loop, but certainly on non-Itanium systems where the
page size is nowhere near 64k, it's arguably pointless. (Can you even
configure an Itanic to have to have a page size > 64k?)
So one way of dealing wih this is making it an inline, and then
#ifdef'ing out the more complex code if the page size is < 64k....
- Ted
next prev parent reply other threads:[~2010-08-03 23:12 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-08-03 22:30 Any qualms about reverting 3d0518f4, ext4: New rec_len encoding for very large blocksizes ? Eric Sandeen
2010-08-03 22:44 ` Andreas Dilger
2010-08-03 22:49 ` Eric Sandeen
2010-08-03 23:12 ` Ted Ts'o [this message]
2010-08-04 0:33 ` Andreas Dilger
2010-08-04 14:21 ` Eric Sandeen
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