From: Vivek Goyal <vgoyal@redhat.com>
To: "Martin K. Petersen" <martin.petersen@oracle.com>
Cc: linux-scsi@vger.kernel.org,
James.Bottomley@hansenpartnership.com, snitzer@redhat.com,
jaxboe@fusionio.com
Subject: Re: [PATCH 1/5] block: Implement support for WRITE SAME
Date: Wed, 15 Feb 2012 10:33:19 -0500 [thread overview]
Message-ID: <20120215153319.GA27312@redhat.com> (raw)
In-Reply-To: <yq1hayugyv4.fsf@sermon.lab.mkp.net>
On Mon, Feb 13, 2012 at 05:19:43PM -0500, Martin K. Petersen wrote:
[..]
>
> block: Mark discard requests unmergeable
>
> Discards were globally marked as mergeable and as a result we had
> several code paths that explicitly disabled merging when REQ_DISCARD was
> set.
>
> Mark discard requests as unmergable and remove special-casing of
> REQ_DISCARD.
Mike Snitzer mentioned that we do allow merging of one discard request
with another except following two cases.
- Don't allow merging of secure discard.
- Don't allow merging of discard request with another non-discard request.
I guess that's why DISCARD requests are mergeable globally and later
we deny merge in selected cases. Do we want to disable that behavior?
[..]
> @@ -591,8 +591,7 @@ void __elv_add_request(struct request_queue *q, struct request *rq, int where)
>
> if (rq->cmd_flags & REQ_SOFTBARRIER) {
> /* barriers are scheduling boundary, update end_sector */
> - if (rq->cmd_type == REQ_TYPE_FS ||
> - (rq->cmd_flags & REQ_DISCARD)) {
> + if (rq->cmd_type == REQ_TYPE_FS) {
This is orthogonal to merging?
[..]
> @@ -634,8 +633,7 @@ void __elv_add_request(struct request_queue *q, struct request *rq, int where)
> if (elv_attempt_insert_merge(q, rq))
> break;
> case ELEVATOR_INSERT_SORT:
> - BUG_ON(rq->cmd_type != REQ_TYPE_FS &&
> - !(rq->cmd_flags & REQ_DISCARD));
> + BUG_ON(rq->cmd_type != REQ_TYPE_FS);
This change also looks orthogonal to merging. Will it not trigger BUG_ON()
when DISCARD request is being inserted into the elevator?
Thanks
Vivek
next prev parent reply other threads:[~2012-02-15 15:33 UTC|newest]
Thread overview: 44+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-01-31 0:31 Write same support Martin K. Petersen
2012-01-31 0:31 ` [PATCH 1/5] block: Implement support for WRITE SAME Martin K. Petersen
2012-02-07 21:40 ` Vivek Goyal
2012-02-13 22:19 ` Martin K. Petersen
2012-02-14 8:05 ` Rolf Eike Beer
2012-02-15 15:33 ` Vivek Goyal [this message]
2012-02-16 3:29 ` Martin K. Petersen
2012-02-16 17:16 ` Vivek Goyal
2012-02-16 19:12 ` Martin K. Petersen
2012-02-08 22:50 ` Mike Snitzer
2012-02-08 23:12 ` Martin K. Petersen
2012-02-09 3:33 ` Mike Snitzer
2012-02-09 3:40 ` Mike Snitzer
2012-01-31 0:31 ` [PATCH 2/5] block: Make blkdev_issue_zeroout use " Martin K. Petersen
2012-01-31 0:31 ` [PATCH 3/5] block: ioctl to zero block ranges Martin K. Petersen
2012-01-31 0:31 ` [PATCH 4/5] scsi: Add a report opcode helper Martin K. Petersen
2012-01-31 19:53 ` Jeff Garzik
2012-01-31 20:16 ` Martin K. Petersen
2012-01-31 0:31 ` [PATCH 5/5] sd: Implement support for WRITE SAME Martin K. Petersen
2012-02-20 16:16 ` Mike Snitzer
2012-02-20 17:36 ` Martin K. Petersen
2012-02-20 18:28 ` Mike Snitzer
2012-02-03 19:15 ` Write same support Mike Snitzer
2012-02-03 19:20 ` Roland Dreier
2012-02-16 20:02 ` Mike Snitzer
2012-02-16 20:46 ` Martin K. Petersen
2012-02-16 21:09 ` Mike Snitzer
2012-02-16 21:03 ` dm-io async WRITE_SAME results in iSCSI NULL pointer [was: Re: Write same support] Mike Snitzer
2012-02-16 21:25 ` Mike Christie
2012-02-16 21:35 ` Mike Snitzer
2012-02-20 17:44 ` Martin K. Petersen
2012-02-20 18:46 ` Mike Snitzer
2012-02-20 23:44 ` Mike Snitzer
2012-02-21 0:07 ` Martin K. Petersen
2012-02-21 3:18 ` Mike Snitzer
2012-02-21 3:57 ` Martin K. Petersen
2012-02-21 6:55 ` Mike Snitzer
2012-02-21 12:31 ` Martin K. Petersen
2012-02-21 14:42 ` Mike Snitzer
2012-02-21 19:33 ` Mike Snitzer
2012-02-21 21:31 ` Martin K. Petersen
2012-02-21 23:36 ` Mike Snitzer
2012-02-21 19:47 ` Vivek Goyal
2012-02-21 19:56 ` Martin K. Petersen
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