From: Mike Snitzer <snitzer@redhat.com>
To: Christoph Hellwig <hch@infradead.org>
Cc: Ming Lin <mlin@kernel.org>, lkml <linux-kernel@vger.kernel.org>,
Jens Axboe <axboe@kernel.dk>,
Kent Overstreet <kent.overstreet@gmail.com>,
Dongsu Park <dpark@posteo.net>,
"Martin K. Petersen" <martin.petersen@oracle.com>,
Ming Lin <ming.l@ssi.samsung.com>,
linux-nvme@lists.infradead.org
Subject: Re: [PATCH v6 05/11] block: remove split code in blkdev_issue_{discard,write_same}
Date: Wed, 21 Oct 2015 12:19:47 -0400 [thread overview]
Message-ID: <20151021161947.GA5212@redhat.com> (raw)
In-Reply-To: <20151021160232.GA5089@redhat.com>
On Wed, Oct 21 2015 at 12:02pm -0400,
Mike Snitzer <snitzer@redhat.com> wrote:
> On Wed, Oct 14 2015 at 9:27am -0400,
> Christoph Hellwig <hch@infradead.org> wrote:
>
> > On Tue, Oct 13, 2015 at 10:44:11AM -0700, Ming Lin wrote:
> > > I just did a quick test with a Samsung 900G NVMe device.
> > > mkfs.xfs is OK on 4.3-rc5.
> > >
> > > What's your device model? I may find a similar one to try.
> >
> > This is a HGST Ultrastar SN100
> >
> > Analsys and tentativ fix below:
> >
> > blktrace for before the commit:
> >
> > 259,0 1 2 0.000002543 2394 G D 0 + 8388607 [mkfs.xfs]
> > 259,0 1 3 0.000008230 2394 I D 0 + 8388607 [mkfs.xfs]
> > 259,0 1 4 0.000031090 207 D D 0 + 8388607 [kworker/1:1H]
> > 259,0 1 5 0.000044869 2394 Q D 8388607 + 8388607 [mkfs.xfs]
> > 259,0 1 6 0.000045992 2394 G D 8388607 + 8388607 [mkfs.xfs]
> > 259,0 1 7 0.000049559 2394 I D 8388607 + 8388607 [mkfs.xfs]
> > 259,0 1 8 0.000061551 207 D D 8388607 + 8388607 [kworker/1:1H]
> >
> > .. and so on.
> >
> > blktrace with the commit:
> >
> > 259,0 2 1 0.000000000 1228 Q D 0 + 4194304 [mkfs.xfs]
> > 259,0 2 2 0.000002543 1228 G D 0 + 4194304 [mkfs.xfs]
> > 259,0 2 3 0.000010080 1228 I D 0 + 4194304 [mkfs.xfs]
> > 259,0 2 4 0.000082187 267 D D 0 + 4194304 [kworker/2:1H]
> > 259,0 2 5 0.000224869 1228 Q D 4194304 + 4194304 [mkfs.xfs]
> > 259,0 2 6 0.000225835 1228 G D 4194304 + 4194304 [mkfs.xfs]
> > 259,0 2 7 0.000229457 1228 I D 4194304 + 4194304 [mkfs.xfs]
> > 259,0 2 8 0.000238507 267 D D 4194304 + 4194304 [kworker/2:1H]
> >
> > So discards are smaller, but better aligned. Now if I tweak a single
> > line in blk-lib.c to be able to use all of bi_size I get the old I/O
> > pattern back and everything works fine again:
> >
> > diff --git a/block/blk-lib.c b/block/blk-lib.c
> > index bd40292..65b61dc 100644
> > --- a/block/blk-lib.c
> > +++ b/block/blk-lib.c
> > @@ -82,7 +82,7 @@ int blkdev_issue_discard(struct block_device *bdev, sector_t sector,
> > break;
> > }
> >
> > - req_sects = min_t(sector_t, nr_sects, MAX_BIO_SECTORS);
> > + req_sects = min_t(sector_t, nr_sects, UINT_MAX >> 9);
> > end_sect = sector + req_sects;
> >
> > bio->bi_iter.bi_sector = sector;
>
> Can we change UINT_MAX >> 9 to rounddown to the first factor of
> minimum_io_size?
>
> That should work for all devices and for dm-thinp (and dm-cache) in
> particular will ensure that all discards that are issued will be a
> multiple of the underlying device's blocksize.
Jeff Moyer pointed out having req_sects be a factor of
discard_granularity makes more sense. And I agree. Same difference in
the end (since dm-thinp sets discard_granularity to the thinp
blocksize).
next prev parent reply other threads:[~2015-10-21 16:19 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-08-12 7:07 [PATCH v6 00/11] simplify block layer based on immutable biovecs Ming Lin
2015-08-12 7:07 ` [PATCH v6 01/11] block: make generic_make_request handle arbitrarily sized bios Ming Lin
2015-08-12 7:07 ` [PATCH v6 02/11] block: simplify bio_add_page() Ming Lin
2015-08-12 7:07 ` [PATCH v6 03/11] bcache: remove driver private bio splitting code Ming Lin
2016-01-08 1:53 ` Eric Wheeler
2015-08-12 7:07 ` [PATCH v6 04/11] btrfs: remove bio splitting and merge_bvec_fn() calls Ming Lin
2015-08-12 7:07 ` [PATCH v6 05/11] block: remove split code in blkdev_issue_{discard,write_same} Ming Lin
2015-10-13 11:50 ` Christoph Hellwig
2015-10-13 17:44 ` Ming Lin
2015-10-14 13:27 ` Christoph Hellwig
2015-10-14 16:38 ` [PATCH v6 05/11] block: remove split code in blkdev_issue_{discard,write_same}B Keith Busch
2015-10-14 16:50 ` Christoph Hellwig
2015-10-21 16:02 ` [PATCH v6 05/11] block: remove split code in blkdev_issue_{discard,write_same} Mike Snitzer
2015-10-21 16:19 ` Mike Snitzer [this message]
2015-10-21 16:33 ` Martin K. Petersen
2015-10-21 17:33 ` Ming Lin
2015-10-21 18:18 ` Mike Snitzer
2015-10-21 20:13 ` Ming Lin
2015-10-22 10:24 ` Christoph Hellwig
2015-10-22 11:22 ` Christoph Hellwig
2015-10-21 7:21 ` Christoph Hellwig
2015-10-21 13:39 ` Jeff Moyer
2015-10-21 15:01 ` Ming Lin
2015-10-21 15:33 ` Mike Snitzer
2015-10-21 17:18 ` Ming Lin
2015-08-12 7:07 ` [PATCH v6 06/11] md/raid5: split bio for chunk_aligned_read Ming Lin
2015-08-12 7:07 ` [PATCH v6 07/11] md/raid5: get rid of bio_fits_rdev() Ming Lin
2015-08-12 7:07 ` [PATCH v6 08/11] block: kill merge_bvec_fn() completely Ming Lin
2015-08-12 7:07 ` [PATCH v6 09/11] fs: use helper bio_add_page() instead of open coding on bi_io_vec Ming Lin
2015-08-12 7:07 ` [PATCH v6 10/11] block: remove bio_get_nr_vecs() Ming Lin
2015-08-12 7:07 ` [PATCH v6 11/11] Documentation: update notes in biovecs about arbitrarily sized bios Ming Lin
2015-08-13 16:51 ` [PATCH v6 00/11] simplify block layer based on immutable biovecs Jens Axboe
2015-08-13 17:03 ` Ming Lin
2015-08-13 17:07 ` Jens Axboe
2015-08-13 17:36 ` Ming Lin
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20151021161947.GA5212@redhat.com \
--to=snitzer@redhat.com \
--cc=axboe@kernel.dk \
--cc=dpark@posteo.net \
--cc=hch@infradead.org \
--cc=kent.overstreet@gmail.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-nvme@lists.infradead.org \
--cc=martin.petersen@oracle.com \
--cc=ming.l@ssi.samsung.com \
--cc=mlin@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).