From: Christoph Hellwig <hch@infradead.org>
To: Damien Le Moal <Damien.LeMoal@wdc.com>
Cc: Christoph Hellwig <hch@infradead.org>,
Johannes Thumshirn <Johannes.Thumshirn@wdc.com>,
Jens Axboe <axboe@kernel.dk>,
linux-block <linux-block@vger.kernel.org>,
Keith Busch <kbusch@kernel.org>,
"linux-scsi @ vger . kernel . org" <linux-scsi@vger.kernel.org>,
"Martin K . Petersen" <martin.petersen@oracle.com>
Subject: Re: [PATCH 09/11] block: Introduce zone write pointer offset caching
Date: Tue, 10 Mar 2020 23:24:06 -0700 [thread overview]
Message-ID: <20200311062406.GA5729@infradead.org> (raw)
In-Reply-To: <BYAPR04MB5816F62B4BB0482359F85AD8E7FC0@BYAPR04MB5816.namprd04.prod.outlook.com>
On Wed, Mar 11, 2020 at 12:34:33AM +0000, Damien Le Moal wrote:
> Yes, I agree with you here. That would be nicer, but early attempt to do so
> failed as we always ended up with potential races on number of zones/wp array
> size in the case of a device change/revalidation. Moving the wp array allocation
> and initialization to blk_revalidate_disk_zones() greatly simplifies the code
> and removes the races as all updates to zone bitmaps, wp array and nr zones are
> done under a queue freeze all together. Moving the wp array only to sd_zbc, even
> using a queue freeze, leads to potential out-of-bounds accesses for the wp array.
>
> Another undesirable side effect of moving the wp array initialization to sd_zbc
> is that we would need another full drive zone report after
> blk_revalidate_disk_zones() own full report. That is costly. On 20TB SMR disks
> with more than 75000 zones, the added delay is significant. Doing all
> initialization within blk_revalidate_disk_zones() full zone report loop avoids
> that added overhead.
That explanation needs to got into the commit log.
next prev parent reply other threads:[~2020-03-11 6:24 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-10 9:46 [PATCH 00/11] Introduce Zone Append for writing to zoned block devices Johannes Thumshirn
2020-03-10 9:46 ` [PATCH 01/11] block: provide fallbacks for blk_queue_zone_is_seq and blk_queue_zone_no Johannes Thumshirn
2020-03-10 9:46 ` [PATCH 02/11] block: Introduce REQ_OP_ZONE_APPEND Johannes Thumshirn
2020-03-10 9:46 ` [PATCH 03/11] block: introduce bio_add_append_page Johannes Thumshirn
2020-03-10 16:43 ` Christoph Hellwig
2020-03-11 18:11 ` Johannes Thumshirn
2020-03-10 9:46 ` [PATCH 04/11] null_blk: Support REQ_OP_ZONE_APPEND Johannes Thumshirn
2020-03-10 16:43 ` Christoph Hellwig
2020-03-10 9:46 ` [PATCH 05/11] block: introduce BLK_STS_ZONE_RESOURCE Johannes Thumshirn
2020-03-10 16:43 ` Christoph Hellwig
2020-03-10 9:46 ` [PATCH 06/11] block: introduce blk_req_zone_write_trylock Johannes Thumshirn
2020-03-10 9:46 ` [PATCH 07/11] block: factor out requeue handling from dispatch code Johannes Thumshirn
2020-03-10 16:44 ` Christoph Hellwig
2020-03-10 9:46 ` [PATCH 08/11] block: delay un-dispatchable request Johannes Thumshirn
2020-03-10 16:45 ` Christoph Hellwig
2020-03-10 9:46 ` [PATCH 09/11] block: Introduce zone write pointer offset caching Johannes Thumshirn
2020-03-10 16:46 ` Christoph Hellwig
2020-03-11 0:34 ` Damien Le Moal
2020-03-11 6:24 ` Christoph Hellwig [this message]
2020-03-11 6:40 ` Damien Le Moal
2020-03-10 9:46 ` [PATCH 10/11] scsi: sd_zbc: factor out sanity checks for zoned commands Johannes Thumshirn
2020-03-10 9:46 ` [PATCH 11/11] scsi: sd_zbc: emulate ZONE_APPEND commands Johannes Thumshirn
2020-03-10 16:42 ` [PATCH 00/11] Introduce Zone Append for writing to zoned block devices Christoph Hellwig
2020-03-11 0:37 ` Damien Le Moal
2020-03-11 6:24 ` Christoph Hellwig
2020-03-11 6:40 ` Damien Le Moal
2020-03-11 7:22 ` Johannes Thumshirn
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=20200311062406.GA5729@infradead.org \
--to=hch@infradead.org \
--cc=Damien.LeMoal@wdc.com \
--cc=Johannes.Thumshirn@wdc.com \
--cc=axboe@kernel.dk \
--cc=kbusch@kernel.org \
--cc=linux-block@vger.kernel.org \
--cc=linux-scsi@vger.kernel.org \
--cc=martin.petersen@oracle.com \
/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).