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From: Christoph Hellwig <hch@lst.de>
To: Minwoo Im <minwoo.im.dev@gmail.com>
Cc: Sagi Grimberg <sagi@grimberg.me>,
	linux-nvme@lists.infradead.org, Jens Axboe <axboe@fb.com>,
	Chao Leng <lengchao@huawei.com>, Keith Busch <kbusch@kernel.org>,
	Christoph Hellwig <hch@lst.de>
Subject: Re: [PATCH V3 3/3] nvme: retry commands based on ACRE flag
Date: Mon, 18 Jan 2021 18:40:51 +0100	[thread overview]
Message-ID: <20210118174051.GA8542@lst.de> (raw)
In-Reply-To: <20210115182602.GA2822@localhost.localdomain>

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.

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  reply	other threads:[~2021-01-18 17:41 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 [this message]
2021-01-19  3:30         ` Minwoo Im
2021-01-19 18:28         ` Keith Busch
2021-01-20  0:52           ` Minwoo Im

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