From: Chris Mason <chris.mason@oracle.com>
To: Arne Jansen <sensille@gmx.net>
Cc: linux-btrfs@vger.kernel.org
Subject: Re: [PATCH] Btrfs: fix submit_worker congestion
Date: Thu, 15 Dec 2011 16:12:03 -0500 [thread overview]
Message-ID: <20111215211203.GN18252@shiny> (raw)
In-Reply-To: <1322599256-15621-1-git-send-email-sensille@gmx.net>
On Tue, Nov 29, 2011 at 09:40:56PM +0100, Arne Jansen wrote:
> Write bios are submitted from the submit_worker. The worker pumps down
> bios into the block layer until it signals a congestion. At least this
> is the theory. In pratice submit_bio just blocks before any signalling
> happens. As the bios are queued per device, this can lead to a situation
> where only one device is served until all bios are submitted, and only
> then the next device is served. This is obviously suboptimal.
> This patch just throws out the congestion detection and reschedules the
> worker every 8 requests. This way, all devices can be kept busy.
> This is only a temporary fix until the block layer provides a non-blocking
> submit_bio. Then the whole submit_worker mechanism can be killed.
Could you please try the top commit in for-linus instead? It seems to
be helping here, although I wasn't able to trigger the same problems you
reported.
-chris
prev parent reply other threads:[~2011-12-15 21:12 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-11-29 20:40 [PATCH] Btrfs: fix submit_worker congestion Arne Jansen
2011-11-29 21:47 ` Chris Mason
2011-11-30 10:30 ` Arne Jansen
2011-11-30 14:13 ` Chris Mason
2011-12-15 21:12 ` Chris Mason [this message]
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