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From: Jeff Moyer <jmoyer@redhat.com>
To: oliver.pntr@gmail.com
Cc: linux-kernel@vger.kernel.org, Adrian Bunk <bunk@kernel.org>,
       Andrew Morton <akpm@linux-foundation.org>,
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Subject: Re: [OP] v2.6.22.22-op1
References: <db9953cd52eb63e471f5fcdcb83b299b@zipernowsky.hu>
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Date: Thu, 01 May 2008 10:47:51 -0400
In-Reply-To: <db9953cd52eb63e471f5fcdcb83b299b@zipernowsky.hu>
	(oliver@zipernowsky.hu's message of "Thu, 01 May 2008 16:32:01 +0200")
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<oliver@zipernowsky.hu> writes:

> I announced the v2.6.22.22-op1 "stable" kernel.

>  fs/aio.c                    |   23 ++++++++++++-----------

> Jeff Moyer (1):
>       aio: account I/O wait time properly

This version of the patch introduced a regression for UML.  It was
seeing 100% iowait time when it wasn't waiting on any I/O.  There was a
follow-up patch which did the io_schedule conditionally, see commit id:

  e00ba3dae077f54cfd2af42e939a618caa7a3bca

Cheers,

Jeff

> diff --git a/fs/aio.c b/fs/aio.c
> index dbe699e..b3419c5 100644
> --- a/fs/aio.c
> +++ b/fs/aio.c
> @@ -1170,7 +1171,7 @@ retry:
>  			ret = 0;
>  			if (to.timed_out)	/* Only check after read evt */
>  				break;
> -			schedule();
> +			io_schedule();
>  			if (signal_pending(tsk)) {
>  				ret = -EINTR;
>  				break;