From: Eric Whitney <eric.whitney@hp.com>
To: Ted Ts'o <tytso@mit.edu>
Cc: Mingming Cao <cmm@us.ibm.com>, linux-ext4@vger.kernel.org
Subject: Re: [PATCH] ext4: Use single thread to perform DIO unwritten convertion
Date: Mon, 07 Mar 2011 10:47:25 -0500 [thread overview]
Message-ID: <4D74FE0D.4090207@hp.com> (raw)
In-Reply-To: <20110305174639.GD11120@thunk.org>
On 03/05/2011 12:46 PM, Ted Ts'o wrote:
> On Thu, Mar 03, 2011 at 11:29:54AM -0800, Mingming Cao wrote:
>> While running ext4 testing on multiple core, we found there are per
>> cpu ext4-dio-unwritten threads processing conversion from unwritten
>> extents to written for IOs completed from async direct IO patch.
>> Per filesystem is enough, we don't need per cpu threads to work on
>> conversion.
>>
>> Signed-off-by: Mingming Cao<cmm@us.ibm.com>
>
> Eric, would you be able to do a very quick sanity check on your
> 48-core machine? I can definitely see how having a huge number of
> threads per file system could be problematic, especially on a system
> with 32 or 64 ext4 file systems. I'm curious though if we'll end up
> taking a performance hit on direct I/O workloads.
>
Hi Ted:
Sure, I can do that - I'll queue it up once I'm done with the "for .39"
patch measurements.
> If I remember correctly we currently have large file create with DIO
> turned off, right? Would it be possible to do a large file create
> with DIO enabled, and do a quick run both with and without this patch?
That's right, we're not measuring DIO right now. I think I've got
enough hardware to run a filesystem per core (or more), and I think it
should be straightforward to write a modified ffsb profile to run (say)
48 filesystems in parallel.
>
> In the future it would also be interesting to see how we are doing
> versus other file systems using a DIO workload. This is a probably
> another area where I suspect some lockstat and oprofile runs may give
> us opportunities for further optimization.
Yes - as discussed at Plumber's. I'll put that on the list as well.
With luck, there should be some time towards the end of the .39 merge
window.
Eric
>
> - Ted
next prev parent reply other threads:[~2011-03-07 15:47 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-03-03 19:29 [PATCH] ext4: Use sing thread to perform DIO unwritten convertion Mingming Cao
2011-03-05 16:54 ` Ted Ts'o
2011-03-05 17:46 ` [PATCH] ext4: Use single " Ted Ts'o
2011-03-07 15:47 ` Eric Whitney [this message]
2011-03-08 1:40 ` Mingming Cao
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=4D74FE0D.4090207@hp.com \
--to=eric.whitney@hp.com \
--cc=cmm@us.ibm.com \
--cc=linux-ext4@vger.kernel.org \
--cc=tytso@mit.edu \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).