From: Minwoo Im <minwoo.im.dev@gmail.com>
To: Keith Busch <kbusch@kernel.org>
Cc: Jens Axboe <axboe@fb.com>, Chao Leng <lengchao@huawei.com>,
Christoph Hellwig <hch@lst.de>,
linux-nvme@lists.infradead.org, Sagi Grimberg <sagi@grimberg.me>
Subject: Re: [PATCH V3 3/3] nvme: retry commands based on ACRE flag
Date: Wed, 20 Jan 2021 09:52:36 +0900 [thread overview]
Message-ID: <20210120005236.GD4205@localhost.localdomain> (raw)
In-Reply-To: <20210119180535.GA1520627@dhcp-10-100-145-180.wdc.com>
On 21-01-20 03:28:38, Keith Busch wrote:
> On Mon, Jan 18, 2021 at 06:40:51PM +0100, Christoph Hellwig wrote:
> > On Sat, Jan 16, 2021 at 03:26:02AM +0900, Minwoo Im wrote:
> > > > I am not sure we should ignore the FAILFAST for non-path errors. If we
> > > > need retryable admin commands, we should let the driver provide a way
> > > > for callers to dispatch requests without that flag.
> > >
> > > Understood. I thought the opposite way about FAILFAST in case with
> > > acre, if device is enabled with acre, all commands would be retried
> > > regardless to FAILFAST... Thanks for pointing that out!
> > >
> > > How do you think which one is right choice to go with if a user-space
> > > application(e.g., nvme-cli) wants a command to be retired in case of
> > > ACRE && Error && !DNR:
> > >
> > > - User-space application should figure out !DNR and retry the command.
> > > (Maybe we are not able to easily figure out exact status code from
> > > the user-space application by the return value).
> > >
> > > - Driver should retry the command right before putting result up to
> > > the user-space even it's a FAILFAST request.
> > >
> > > Thanks,
> >
> > We could come up with a version of the ioctls that use the normal
> > retry mechanisms. nvme_passthru_cmd64 has two reserved fields we
> > could use for UAPI flags like this.
>
> Yeah, I'm totally okay with adding driver control flags for this sort of
> behavior.
>
> For the moment, the ioctl interface has always been 1:1 for commands
> submitted to completions received, so all user space applications using
> this should have been prepared to receive unfiltered status back and
> handle retries on their own.
Thanks Keith for your feedback!
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prev parent reply other threads:[~2021-01-20 0:52 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-14 13:31 [PATCH V3 0/3] nvme: fixes for command retry Minwoo Im
2021-01-14 13:31 ` [PATCH V3 1/3] nvme: check all retry delay times in Identify Controller Minwoo Im
2021-01-19 3:43 ` Minwoo Im
2021-01-14 13:31 ` [PATCH V3 2/3] nvme: introduce acre flag in nvme_ctrl Minwoo Im
2021-01-15 2:16 ` Chao Leng
2021-01-14 13:31 ` [PATCH V3 3/3] nvme: retry commands based on ACRE flag Minwoo Im
2021-01-15 2:17 ` Chao Leng
2021-01-15 17:04 ` Keith Busch
2021-01-15 18:26 ` Minwoo Im
2021-01-18 17:40 ` Christoph Hellwig
2021-01-19 3:30 ` Minwoo Im
2021-01-19 18:28 ` Keith Busch
2021-01-20 0:52 ` Minwoo Im [this message]
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