From: Christoph Hellwig <hch@lst.de>
To: Chaitanya Kulkarni <Chaitanya.Kulkarni@wdc.com>
Cc: "Martin K. Petersen" <martin.petersen@oracle.com>,
Christoph Hellwig <hch@lst.de>, Ming Lei <ming.lei@redhat.com>,
"linux-block@vger.kernel.org" <linux-block@vger.kernel.org>,
"linux-nvme@lists.infradead.org" <linux-nvme@lists.infradead.org>,
Bart Van Assche <bvanassche@acm.org>
Subject: Re: Regression: NVMe: kernel BUG at lib/sg_pool.c:103!
Date: Thu, 21 Feb 2019 14:37:00 +0100 [thread overview]
Message-ID: <20190221133700.GA20189@lst.de> (raw)
In-Reply-To: <722BE5B7-B32B-4B2F-9AC2-E6F5AB5E12D4@wdc.com>
On Thu, Feb 21, 2019 at 01:29:57AM +0000, Chaitanya Kulkarni wrote:
> Hi Martin,
>
> I don't mind going though that route, here are some points about
> benefits of not using REQ_SPECIAL_PAYLOAD for write-zeroes :-
>
> 1. We are using RQF_SPECIAL_PAYLOAD for only discard commands and not for
> write-zeroes because it does not have any payload. Using this in the code will
> trigger more code changes to handle in the completion path.
Yes. And that is the big difference to SCSI where REQ_OP_WRITE_ZEROES
turns into a WRITE SAME command that has a payload. So for SCSI
RQF_SPECIAL_PAYLOAD for REQ_OP_WRITE_ZEROES makes a lot of sense, for
NVMe it does not.
WARNING: multiple messages have this Message-ID (diff)
From: hch@lst.de (Christoph Hellwig)
Subject: Regression: NVMe: kernel BUG at lib/sg_pool.c:103!
Date: Thu, 21 Feb 2019 14:37:00 +0100 [thread overview]
Message-ID: <20190221133700.GA20189@lst.de> (raw)
In-Reply-To: <722BE5B7-B32B-4B2F-9AC2-E6F5AB5E12D4@wdc.com>
On Thu, Feb 21, 2019@01:29:57AM +0000, Chaitanya Kulkarni wrote:
> Hi Martin,
>
> I don't mind going though that route, here are some points about
> benefits of not using REQ_SPECIAL_PAYLOAD for write-zeroes :-
>
> 1. We are using RQF_SPECIAL_PAYLOAD for only discard commands and not for
> write-zeroes because it does not have any payload. Using this in the code will
> trigger more code changes to handle in the completion path.
Yes. And that is the big difference to SCSI where REQ_OP_WRITE_ZEROES
turns into a WRITE SAME command that has a payload. So for SCSI
RQF_SPECIAL_PAYLOAD for REQ_OP_WRITE_ZEROES makes a lot of sense, for
NVMe it does not.
next prev parent reply other threads:[~2019-02-21 13:37 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-02-20 3:11 Regression: NVMe: kernel BUG at lib/sg_pool.c:103! Ming Lei
2019-02-20 3:11 ` Ming Lei
2019-02-20 3:13 ` Ming Lei
2019-02-20 3:13 ` Ming Lei
2019-02-20 14:17 ` Christoph Hellwig
2019-02-20 14:17 ` Christoph Hellwig
2019-02-20 16:59 ` Chaitanya Kulkarni
2019-02-20 16:59 ` Chaitanya Kulkarni
2019-02-20 18:16 ` Chaitanya Kulkarni
2019-02-20 18:16 ` Chaitanya Kulkarni
2019-02-20 22:55 ` Martin K. Petersen
2019-02-20 22:55 ` Martin K. Petersen
2019-02-21 1:29 ` Chaitanya Kulkarni
2019-02-21 1:29 ` Chaitanya Kulkarni
2019-02-21 13:37 ` Christoph Hellwig [this message]
2019-02-21 13:37 ` Christoph Hellwig
2019-02-21 14:22 ` Martin K. Petersen
2019-02-21 14:22 ` Martin K. Petersen
2019-02-21 2:16 ` Ming Lei
2019-02-21 2:16 ` Ming Lei
2019-02-21 2:21 ` Chaitanya Kulkarni
2019-02-21 2:21 ` Chaitanya Kulkarni
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=20190221133700.GA20189@lst.de \
--to=hch@lst.de \
--cc=Chaitanya.Kulkarni@wdc.com \
--cc=bvanassche@acm.org \
--cc=linux-block@vger.kernel.org \
--cc=linux-nvme@lists.infradead.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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.