From: Vivek Goyal <vgoyal@redhat.com>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Fengguang Wu <fengguang.wu@intel.com>,
LKML <linux-kernel@vger.kernel.org>,
"Myklebust, Trond" <Trond.Myklebust@netapp.com>,
linux-fsdevel@vger.kernel.org,
Linux Memory Management List <linux-mm@kvack.org>,
Jens Axboe <axboe@kernel.dk>
Subject: Re: write-behind on streaming writes
Date: Wed, 6 Jun 2012 12:15:44 -0400 [thread overview]
Message-ID: <20120606161544.GA8133@redhat.com> (raw)
In-Reply-To: <20120606121408.GB4934@redhat.com>
On Wed, Jun 06, 2012 at 08:14:08AM -0400, Vivek Goyal wrote:
[..]
> I think it is happening because sync_file_range() will send all
> the writes as SYNC and it will compete with firefox IO. On the other
> hand, flusher's IO will show up as ASYNC and CFQ will be penalize it
> heavily and firefox's IO will be prioritized. And this effect should
> just get worse as more processes do sync_file_range().
Ok, this time I tried the same test again but with 4 processes doing
writes in parallel on 4 different files.
And with sync_file_range() things turned ugly. Interactivity was very poor.
firefox launch test took around 1m:45s with sync_file range() while it
took only about 35seconds with regular flusher threads.
So sending writeback IO synchronously wreaks havoc.
Thanks
Vivek
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next prev parent reply other threads:[~2012-06-06 16:15 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20120528114124.GA6813@localhost>
[not found] ` <CA+55aFxHt8q8+jQDuoaK=hObX+73iSBTa4bBWodCX3s-y4Q1GQ@mail.gmail.com>
2012-05-29 15:57 ` write-behind on streaming writes Fengguang Wu
2012-05-29 17:35 ` Linus Torvalds
2012-05-30 3:21 ` Fengguang Wu
2012-06-05 1:01 ` Dave Chinner
2012-06-05 17:18 ` Vivek Goyal
2012-06-05 17:23 ` Vivek Goyal
2012-06-05 17:41 ` Vivek Goyal
2012-06-05 18:48 ` Vivek Goyal
2012-06-05 20:10 ` Vivek Goyal
2012-06-06 2:57 ` Vivek Goyal
2012-06-06 3:14 ` Linus Torvalds
2012-06-06 12:14 ` Vivek Goyal
2012-06-06 14:00 ` Fengguang Wu
2012-06-06 17:04 ` Vivek Goyal
2012-06-07 9:45 ` Jan Kara
2012-06-07 19:06 ` Vivek Goyal
2012-06-06 16:15 ` Vivek Goyal [this message]
2012-06-06 14:08 ` Fengguang Wu
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