From: Alan Stern <stern@rowland.harvard.edu> To: Andrea Vai <andrea.vai@unipv.it> Cc: Damien Le Moal <Damien.LeMoal@wdc.com>, Johannes Thumshirn <jthumshirn@suse.de>, Jens Axboe <axboe@kernel.dk>, USB list <linux-usb@vger.kernel.org>, SCSI development list <linux-scsi@vger.kernel.org>, Himanshu Madhani <himanshu.madhani@cavium.com>, Hannes Reinecke <hare@suse.com>, Ming Lei <ming.lei@redhat.com>, Omar Sandoval <osandov@fb.com>, "Martin K. Petersen" <martin.petersen@oracle.com>, Greg KH <gregkh@linuxfoundation.org>, Hans Holmberg <Hans.Holmberg@wdc.com> Subject: Re: Slow I/O on USB media after commit f664a3cc17b7d0a2bc3b3ab96181e1029b0ec0e6 Date: Wed, 25 Sep 2019 15:30:16 -0400 (EDT) Message-ID: <Pine.LNX.4.44L0.1909251524520.6072-300000@netrider.rowland.org> (raw) In-Reply-To: <981fc98a9995eaee5f65709cacc46f13a2c603ad.camel@unipv.it> [-- Attachment #1: Type: TEXT/PLAIN, Size: 920 bytes --] On Fri, 20 Sep 2019, Andrea Vai wrote: > Il giorno gio, 19/09/2019 alle 14.14 +0000, Damien Le Moal ha scritto: > > On 2019/09/19 16:01, Alan Stern wrote: > > [...] > > > No doubt Andrea will be happy to test your fix when it's ready. > > Yes, of course. > > > > > Hannes posted an RFC series: > > > > https://www.spinics.net/lists/linux-scsi/msg133848.html > > > > Andrea can try it. > > Ok, but I would need some instructions please, because I am not able > to understand how to "try it". Sorry for that. I have attached the two patches to this email. You should start with a recent kernel source tree and apply the patches by doing: git apply patch1 patch2 or something similar. Then build a kernel from the new source code and test it. Ultimately, if nobody can find a way to restore the sequential I/O behavior we had prior to commit f664a3cc17b7, that commit may have to be reverted. Alan Stern [-- Attachment #2: Type: TEXT/PLAIN, Size: 980 bytes --] From: Hannes Reinecke <hare@suse.com> When blk_mq_request_issue_directly() returns BLK_STS_RESOURCE we need to requeue the I/O, but adding it to the global request list will mess up with the passed-in request list. So re-add the request to the original list and leave it to the caller to handle situations where the list wasn't completely emptied. Signed-off-by: Hannes Reinecke <hare@suse.com> --- block/blk-mq.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/block/blk-mq.c b/block/blk-mq.c index b038ec680e84..44ff3c1442a4 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -1899,8 +1899,7 @@ void blk_mq_try_issue_list_directly(struct blk_mq_hw_ctx *hctx, if (ret != BLK_STS_OK) { if (ret == BLK_STS_RESOURCE || ret == BLK_STS_DEV_RESOURCE) { - blk_mq_request_bypass_insert(rq, - list_empty(list)); + list_add(list, &rq->queuelist); break; } blk_mq_end_request(rq, ret); -- 2.16.4 [-- Attachment #3: Type: TEXT/PLAIN, Size: 1721 bytes --] From: Hannes Reinecke <hare@suse.com> A scheduler might be attached even for devices exposing more than one hardware queue, so the check for the number of hardware queue is pointless and should be removed. Signed-off-by: Hannes Reinecke <hare@suse.com> --- block/blk-mq.c | 6 +----- 1 file changed, 1 insertion(+), 5 deletions(-) diff --git a/block/blk-mq.c b/block/blk-mq.c index 44ff3c1442a4..faab542e4836 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -1931,7 +1931,6 @@ static void blk_add_rq_to_plug(struct blk_plug *plug, struct request *rq) static blk_qc_t blk_mq_make_request(struct request_queue *q, struct bio *bio) { - const int is_sync = op_is_sync(bio->bi_opf); const int is_flush_fua = op_is_flush(bio->bi_opf); struct blk_mq_alloc_data data = { .flags = 0}; struct request *rq; @@ -1977,7 +1976,7 @@ static blk_qc_t blk_mq_make_request(struct request_queue *q, struct bio *bio) /* bypass scheduler for flush rq */ blk_insert_flush(rq); blk_mq_run_hw_queue(data.hctx, true); - } else if (plug && (q->nr_hw_queues == 1 || q->mq_ops->commit_rqs)) { + } else if (plug && q->mq_ops->commit_rqs) { /* * Use plugging if we have a ->commit_rqs() hook as well, as * we know the driver uses bd->last in a smart fashion. @@ -2020,9 +2019,6 @@ static blk_qc_t blk_mq_make_request(struct request_queue *q, struct bio *bio) blk_mq_try_issue_directly(data.hctx, same_queue_rq, &cookie); } - } else if ((q->nr_hw_queues > 1 && is_sync) || (!q->elevator && - !data.hctx->dispatch_busy)) { - blk_mq_try_issue_directly(data.hctx, rq, &cookie); } else { blk_mq_sched_insert_request(rq, false, true, true); } -- 2.16.4
next prev parent reply index Thread overview: 120+ messages / expand[flat|nested] mbox.gz Atom feed top [not found] <307581a490b610c3025ee80f79a465a89d68ed19.camel@unipv.it> 2019-08-20 17:13 ` Alan Stern 2019-08-23 10:39 ` Andrea Vai 2019-08-23 20:42 ` Alan Stern 2019-08-26 6:09 ` Andrea Vai 2019-08-26 16:33 ` Alan Stern 2019-09-18 15:25 ` Andrea Vai 2019-09-18 16:30 ` Alan Stern 2019-09-19 7:33 ` Andrea Vai 2019-09-19 17:54 ` Alan Stern 2019-09-20 7:25 ` Andrea Vai 2019-09-20 7:44 ` Greg KH 2019-09-19 8:26 ` Damien Le Moal 2019-09-19 8:55 ` Ming Lei 2019-09-19 9:09 ` Damien Le Moal 2019-09-19 9:21 ` Ming Lei 2019-09-19 14:01 ` Alan Stern 2019-09-19 14:14 ` Damien Le Moal 2019-09-20 7:03 ` Andrea Vai 2019-09-25 19:30 ` Alan Stern [this message] 2019-09-25 19:36 ` Jens Axboe 2019-09-27 15:47 ` Andrea Vai 2019-11-04 16:00 ` Andrea Vai 2019-11-04 18:20 ` Alan Stern 2019-11-05 11:48 ` Andrea Vai 2019-11-05 18:31 ` Alan Stern 2019-11-05 23:29 ` Jens Axboe 2019-11-06 16:03 ` Alan Stern 2019-11-06 22:13 ` Damien Le Moal 2019-11-07 7:04 ` Andrea Vai 2019-11-07 7:54 ` Damien Le Moal 2019-11-07 18:59 ` Andrea Vai 2019-11-08 8:42 ` Damien Le Moal 2019-11-08 14:33 ` Jens Axboe 2019-11-11 10:46 ` Andrea Vai 2019-11-09 10:09 ` Ming Lei 2019-11-09 22:28 ` Ming Lei 2019-11-11 10:50 ` Andrea Vai 2019-11-11 11:05 ` Ming Lei 2019-11-11 11:13 ` Andrea Vai 2019-11-22 19:16 ` Andrea Vai 2019-11-23 7:28 ` Ming Lei 2019-11-23 15:44 ` Andrea Vai 2019-11-25 3:54 ` Ming Lei 2019-11-25 10:11 ` Andrea Vai 2019-11-25 10:29 ` Ming Lei 2019-11-25 14:58 ` Andrea Vai 2019-11-25 15:15 ` Ming Lei 2019-11-25 18:51 ` Andrea Vai 2019-11-26 2:32 ` Ming Lei 2019-11-26 7:46 ` Andrea Vai 2019-11-26 9:15 ` Ming Lei 2019-11-26 10:24 ` Ming Lei 2019-11-26 11:14 ` Andrea Vai 2019-11-27 2:05 ` Ming Lei 2019-11-27 9:39 ` Andrea Vai 2019-11-27 13:08 ` Ming Lei 2019-11-27 15:01 ` Andrea Vai 2019-11-27 0:21 ` Finn Thain 2019-11-27 8:14 ` AW: " Schmid, Carsten 2019-11-27 21:49 ` Finn Thain 2019-11-28 7:46 ` Andrea Vai 2019-11-28 8:12 ` AW: " Schmid, Carsten 2019-11-28 11:40 ` Andrea Vai 2019-11-28 17:39 ` Alan Stern 2019-11-28 9:17 ` Ming Lei 2019-11-28 17:34 ` Andrea Vai 2019-11-29 0:57 ` Ming Lei 2019-11-29 2:35 ` Ming Lei 2019-11-29 14:41 ` Andrea Vai 2019-12-03 2:23 ` Ming Lei 2019-12-10 7:35 ` Andrea Vai 2019-12-10 8:05 ` Ming Lei 2019-12-11 2:41 ` Theodore Y. Ts'o 2019-12-11 4:00 ` Ming Lei 2019-12-11 16:07 ` Theodore Y. Ts'o 2019-12-11 21:33 ` Ming Lei 2019-12-12 7:34 ` Andrea Vai 2019-12-18 8:25 ` Andrea Vai 2019-12-18 9:48 ` Ming Lei [not found] ` <b1b6a0e9d690ecd9432025acd2db4ac09f834040.camel@unipv.it> 2019-12-23 13:08 ` Ming Lei 2019-12-23 14:02 ` Andrea Vai 2019-12-24 1:32 ` Ming Lei 2019-12-24 8:04 ` Andrea Vai 2019-12-24 8:47 ` Ming Lei 2019-12-23 16:26 ` Theodore Y. Ts'o 2019-12-23 16:29 ` Andrea Vai 2019-12-23 17:22 ` Theodore Y. Ts'o 2019-12-23 18:45 ` Andrea Vai 2019-12-23 19:53 ` Theodore Y. Ts'o 2019-12-24 1:27 ` Ming Lei 2019-12-24 6:49 ` Andrea Vai 2019-12-24 8:51 ` Andrea Vai 2019-12-24 9:35 ` Ming Lei 2019-12-25 5:17 ` Theodore Y. Ts'o 2019-12-26 2:27 ` Ming Lei 2019-12-26 3:30 ` Theodore Y. Ts'o 2019-12-26 8:37 ` Ming Lei 2020-01-07 7:51 ` Andrea Vai [not found] ` <20200101074310.10904-1-hdanton@sina.com> 2020-01-01 13:53 ` slow IO on USB media Ming Lei 2019-11-29 11:44 ` AW: Slow I/O on USB media after commit f664a3cc17b7d0a2bc3b3ab96181e1029b0ec0e6 Bernd Schubert 2019-12-02 7:01 ` Andrea Vai 2019-11-28 17:10 ` Andrea Vai [not found] <e3f87757f7a0fdf551e911ad32fc8122eebe04c7.camel@unipv.it> 2019-08-13 19:52 ` Alan Stern 2019-07-02 10:46 Andrea Vai 2019-07-02 11:51 ` Johannes Thumshirn 2019-07-02 22:36 ` Andrea Vai 2019-07-03 7:29 ` Johannes Thumshirn 2019-07-03 14:23 ` Alan Stern 2019-07-06 22:06 ` Andrea Vai 2019-07-08 15:38 ` Alan Stern 2019-07-02 12:01 ` Ming Lei 2019-07-02 22:39 ` Andrea Vai 2019-07-03 2:01 ` Ming Lei 2019-07-03 5:11 ` Andrea Vai 2019-07-03 6:36 ` Ming Lei 2019-07-03 15:27 ` Chris Murphy 2019-07-06 9:33 ` Andrea Vai 2019-07-08 1:01 ` Ming Lei 2019-07-09 21:18 ` Andrea Vai 2019-07-10 2:44 ` Ming Lei
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