We will get around to reformatting our spindles to some other FS after we get as much data and analysis out of our current configuration as we can get. 
We'll report out our findings on the lock contention, and throughput data for some other FS then.  I'd like recommendations on what file systems to try, besides ext2.
First I need to re-run the lock meter test making sure the block-highmem is in or otherwise not skewing our data.


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-----Original Message-----
From: Russell Leighton [mailto:russ@elegant-software.com]
Sent: Thursday, June 20, 2002 5:36 AM
To: Andrew Morton
Cc: mgross@unix-os.sc.intel.com; Linux Kernel Mailing List; lse-tech@lists.sourceforge.net; richard.a.griffiths@intel.com
Subject: [Lse-tech] Re: ext3 performance bottleneck as the number of spindles gets large

Is this a property of ext3 only or the vfs? ... the real question being: will ext2 or some of the other
"major" filesystems like reiser perform better?

Andrew Morton wrote:
mgross wrote:
Has anyone done any work looking into the I/O scaling of Linux / ext3 per
spindle or per adapter? We would like to compare notes.

No. ext3 scalability is very poor, I'm afraid. The fs really wasn't
up and running until kernel 2.4.5 and we just didn't have time to
address that issue.

I've only just started to look at the ext3 code but it seems to me that replacing the
BKL with a per - ext3 file system lock could remove some of the contention thats
getting measured. What data are the BKL protecting in these ext3 functions? Could a
lock per FS approach work?

The vague plan there is to replace lock_kernel with lock_journal
where appropriate. But ext3 scalability work of this nature
will be targetted at the 2.5 kernel, most probably.

I'll take a look, see if there's any low-hanging fruit in there,
but I doubt that the results will be fantastic.

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