From mboxrd@z Thu Jan  1 00:00:00 1970
From: j.neuschaefer@gmx.net (Jonathan =?utf-8?Q?Neusch=C3=A4fer?=)
Date: Mon, 8 Aug 2011 16:55:35 +0200
Subject: difference between io_schedule() and schedule()
In-Reply-To: <CAAYFAvqu4Eqi5tdv4-dskMgFqhH5VNGJn9wyxZ9VLDFA_p4efQ@mail.gmail.com>
References: <CAAYFAvqu4Eqi5tdv4-dskMgFqhH5VNGJn9wyxZ9VLDFA_p4efQ@mail.gmail.com>
Message-ID: <20110808145535.GA2434@debian.debian>
To: kernelnewbies@lists.kernelnewbies.org
List-Id: kernelnewbies.lists.kernelnewbies.org

On Sat, Aug 06, 2011 at 12:31:21PM +0530, Rajat Sharma wrote:
> Hi All,
> 
> What is the difference between io_schedule() and schedule(), is
> io_schedule() more restrictive to shedule only I/O bound processes or
> it just favours I/O bound processes. Any documentation link would be
> great help.

Have you even looked at the source code?

>>From kernel/sched.c +5721:
/*
 * This task is about to go to sleep on IO. Increment rq->nr_iowait so
 * that process accounting knows that this is a task in IO wait state.
 */
void __sched io_schedule(void)
{
	struct rq *rq = raw_rq();

	delayacct_blkio_start();
	atomic_inc(&rq->nr_iowait);
	blk_flush_plug(current);
	current->in_iowait = 1;
	schedule();
	current->in_iowait = 0;
	atomic_dec(&rq->nr_iowait);
	delayacct_blkio_end();
}
EXPORT_SYMBOL(io_schedule);

HTH,
	Jonathan Neusch?fer