From: Keith Busch <kbusch@kernel.org>
To: Bart Van Assche <bvanassche@acm.org>
Cc: Jens Axboe <axboe@kernel.dk>,
linux-block@vger.kernel.org, Christoph Hellwig <hch@lst.de>,
"Martin K . Petersen" <martin.petersen@oracle.com>,
Ming Lei <ming.lei@redhat.com>,
Damien Le Moal <damien.lemoal@opensource.wdc.com>,
Ed Tsai <ed.tsai@mediatek.com>
Subject: Re: [PATCH v2] block: Improve shared tag set performance
Date: Thu, 19 Jan 2023 11:47:53 -0700 [thread overview]
Message-ID: <Y8mQWTRze+SXD7Oz@kbusch-mbp> (raw)
In-Reply-To: <4be69fc0-af32-b552-6a36-f75eb798ca95@acm.org>
On Wed, Jan 18, 2023 at 02:46:38PM -0800, Bart Van Assche wrote:
> - The code removed by this patch negatively impacts performance of all
> SCSI hosts with two or more data LUNs and also of all NVMe controllers
> that export two or more namespaces if there are significant
> differences in the number of I/O operations per second for different
> LUNs/namespaces. This is why I think that this should be solved in the
> block layer instead of modifying each block driver individually.
I think the potential performance sacrifice was done on purpose in order
to guarantee all tagset subscribers can have at least one unblocked
access to the pool, otherwise one LUN could starve all the others by
tying up all the tags in long-running operations. Is anyone actually
benefiting from the current sharing, though? I really do not know, so
I'm having trouble weighing in on removing it.
next prev parent reply other threads:[~2023-01-19 18:48 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-01-03 19:53 [PATCH v2] block: Improve shared tag set performance Bart Van Assche
2023-01-18 21:20 ` Bart Van Assche
2023-01-18 22:14 ` Keith Busch
2023-01-18 22:46 ` Bart Van Assche
2023-01-19 17:48 ` Bart Van Assche
2023-01-19 18:47 ` Keith Busch [this message]
2023-01-19 19:28 ` Bart Van Assche
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=Y8mQWTRze+SXD7Oz@kbusch-mbp \
--to=kbusch@kernel.org \
--cc=axboe@kernel.dk \
--cc=bvanassche@acm.org \
--cc=damien.lemoal@opensource.wdc.com \
--cc=ed.tsai@mediatek.com \
--cc=hch@lst.de \
--cc=linux-block@vger.kernel.org \
--cc=martin.petersen@oracle.com \
--cc=ming.lei@redhat.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