From: Nikanth Karthikesan <knikanth@suse.de>
Organization: suse.de
To: Jens Axboe <jens.axboe@oracle.com>
Subject: Re: [PATCH] Fix discard requests accounting in the diskstats
Date: Fri, 17 Apr 2009 13:25:01 +0530
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Cc: David Woodhouse <David.Woodhouse@intel.com>, linux-kernel@vger.kernel.org,
       jmarchan@redhat.com
References: <200904171144.49448.knikanth@suse.de> <20090417064912.GH4593@kernel.dk>
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On Friday 17 April 2009 12:19:12 Jens Axboe wrote:
> On Fri, Apr 17 2009, Nikanth Karthikesan wrote:
> > When 2 discard requests are merged, the stats gets updated, but we do not
> > update statistics normally when a discard request is issued or completed.
> > For example the in_flight counter would be decremented when 2 discard
> > requests are merged, but it was not at all incremented when they were
> > issued, and in_flight counter will not be decremented, when they are
> > completed as well.
> >
> > This patch fixes this by adding discard requests to the statistics.
>
> This needs rebasing on top of this one:
>
> http://lkml.org/lkml/2009/4/16/159
>
> whenever that gets resubmitted as a proper, working patch.
>

Ok. I will resend after Jerome resubmits that patch.

Thanks
Nikanth
 
> > Signed-off-by: Nikanth Karthikesan <knikanth@suse.de>
> >
> > ---
> >
> > diff --git a/block/blk-core.c b/block/blk-core.c
> > index 07ab754..ee960a7 100644
> > --- a/block/blk-core.c
> > +++ b/block/blk-core.c
> > @@ -68,7 +68,7 @@ static void drive_stat_acct(struct request *rq, int
> > new_io) int rw = rq_data_dir(rq);
> >  	int cpu;
> >
> > -	if (!blk_fs_request(rq) || !blk_do_io_stat(rq))
> > +	if (!rq_accountable(rq) || !blk_do_io_stat(rq))
> >  		return;
> >
> >  	cpu = part_stat_lock();
> > @@ -1698,7 +1698,7 @@ static void blk_account_io_done(struct request
> > *req) * IO on queueing nor completion.  Accounting the containing
> >  	 * request is enough.
> >  	 */
> > -	if (blk_fs_request(req) && req != &req->q->bar_rq) {
> > +	if (rq_accountable(req) && req != &req->q->bar_rq) {
> >  		unsigned long duration = jiffies - req->start_time;
> >  		const int rw = rq_data_dir(req);
> >  		struct hd_struct *part;
> > diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
> > index ba54c83..9483c02 100644
> > --- a/include/linux/blkdev.h
> > +++ b/include/linux/blkdev.h
> > @@ -667,7 +667,9 @@ static inline void blk_clear_queue_full(struct
> > request_queue *q, int sync) (REQ_NOMERGE | REQ_STARTED | REQ_HARDBARRIER
> > | REQ_SOFTBARRIER) #define rq_mergeable(rq)	\
> >  	(!((rq)->cmd_flags & RQ_NOMERGE_FLAGS) && \
> > -	 (blk_discard_rq(rq) || blk_fs_request((rq))))
> > +	 (blk_discard_rq(rq) || blk_fs_request(rq)))
> > +#define rq_accountable(rq)	\
> > +	(blk_discard_rq(rq) || blk_fs_request(rq))
> >
> >  /*
> >   * q->prep_rq_fn return values


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