Date: Mon, 10 Jan 2011 14:18:26 -0500
From: Christoph Hellwig <hch@infradead.org>
To: Michael Monnerie <michael.monnerie@is.it-management.at>
Cc: xfs@oss.sgi.com
Subject: Re: [PATCH] xfs_repair: multithread phase 2
Message-ID: <20110110191826.GB25029@infradead.org>
References: <1294620248-17098-1-git-send-email-david@fromorbit.com>
 <201101100857.53421@zmi.at>
 <20110110084122.GF28803@dastard>
 <201101101425.48134@zmi.at>
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On Mon, Jan 10, 2011 at 02:25:47PM +0100, Michael Monnerie wrote:
> On Montag, 10. Januar 2011 Dave Chinner wrote:
> > Pretty much
> > every sata disk supports NCQ these days, and default to a depth of
> > 32, which means we can have 32 concurrent reads in progress at once.
> > Phase 2 is all synchronous IO, so the only way to hide the IO
> > latency is to queue work to multiple threads and switch between the
> > threadsto work on another queue when the current one blocks waiting
> > for IO.
> 
> This is interesting. Did you measure this with a rotating single disk? 

Take a look at the patch description.