From: Eric Sandeen <sandeen@redhat.com>
To: Bill Fink <bill@wizard.sci.gsfc.nasa.gov>
Cc: Bill Fink <billfink@mindspring.com>,
"tytso@mit.edu" <tytso@mit.edu>,
"adilger@sun.com" <adilger@sun.com>,
"linux-ext4@vger.kernel.org" <linux-ext4@vger.kernel.org>,
"Fink, William E. (GSFC-6061)" <william.e.fink@nasa.gov>
Subject: Re: [RFC PATCH] ext4: fix 50% disk write performance regression
Date: Mon, 30 Aug 2010 14:35:53 -0500 [thread overview]
Message-ID: <4C7C0819.8040505@redhat.com> (raw)
In-Reply-To: <20100830153025.302fa359.bill@wizard.sci.gsfc.nasa.gov>
Bill Fink wrote:
> On Mon, 30 Aug 2010, Eric Sandeen wrote:
...
>> When I get some time (soon I hope) I'll look into the ramifications
>> of this change (i.e. what if wbc->nr_to_write * 8 is more than the dirty
>> pages, do things work out ok?) but it seems pretty reasonable.
>
> In thinking about that issue, my non-expert thought was that
> if desired_nr_to_write was larger, it hopefully wouldn't be an
> issue since presumably it's only going to actually write at most
> the number of dirty pages anyway. And on the flip side, there
> doesn't seem to be an issue with desired_nr_to_write possibly
> being smaller that it was without the patch, since the empirical
> evidence is that the performance significantly improved with the
> patch, and the effect of a lower value would presumably be
> reduced performance.
>
> -Bill
Ted's suggestion of capturing blktrace data would be a really great
step towards understanding what changed, too.
Thanks!
-Eric
next prev parent reply other threads:[~2010-08-30 19:36 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-08-30 3:11 [RFC PATCH] ext4: fix 50% disk write performance regression Bill Fink
2010-08-30 17:05 ` Eric Sandeen
2010-08-30 19:30 ` Bill Fink
2010-08-30 19:35 ` Eric Sandeen [this message]
2010-08-30 17:40 ` Ted Ts'o
2010-08-30 20:49 ` Bill Fink
2010-08-30 21:05 ` Eric Sandeen
[not found] ` <20100830194533.6d09c38b.bill@wizard.sci.gsfc.nasa.gov>
2010-08-30 23:53 ` Eric Sandeen
[not found] ` <20100830210541.8b248a14.billfink@mindspring.com>
[not found] ` <4C7C62E9.4090707@redhat.com>
2010-08-31 3:27 ` Bill Fink
2010-08-31 3:29 ` Eric Sandeen
2010-08-31 0:37 ` Ted Ts'o
2010-08-31 0:51 ` Justin Maggard
2010-08-31 1:44 ` Bill Fink
2010-08-31 1:14 ` Bill Fink
2010-08-31 3:43 ` [PATCH] " Eric Sandeen
2010-08-31 4:26 ` Eric Sandeen
2010-08-31 4:53 ` Bill Fink
2010-08-31 5:05 ` Eric Sandeen
2010-08-31 5:31 ` Bill Fink
2010-09-09 0:23 ` Daniel Taylor
2010-09-09 3:29 ` Eric Sandeen
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