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From: "Martin K. Petersen" <martin.petersen@oracle.com>
To: Damien Le Moal <damien.lemoal@wdc.com>
Cc: Jens Axboe <axboe@kernel.dk>, Sagi Grimberg <sagi@grimberg.me>,
	linux-nvme@lists.infradead.org, linux-block@vger.kernel.org,
	Keith Busch <kbusch@kernel.org>, Christoph Hellwig <hch@lst.de>
Subject: Re: [PATCH] nvme: Fix io_opt limit setting
Date: Wed, 13 May 2020 23:29:53 -0400	[thread overview]
Message-ID: <yq1a72bw5vy.fsf@oracle.com> (raw)
In-Reply-To: <20200514015452.1055278-1-damien.lemoal@wdc.com> (Damien Le Moal's message of "Thu, 14 May 2020 10:54:52 +0900")


Damien,

> results in blk_stack_limits() to return an error when the combined
> devices have different but compatible physical sector sizes (e.g. 512B
> sector SSD with 4KB sector disks).

We'll need to get that stacking logic fixed up to take io_opt into
account when scaling pbs/min. Just as a safety measure in case we don't
catch devices reporting crazy values in the LLDs.

> Fix this by not setting the optiomal IO size limit if the namespace

optimal

> does not report an optimal write size value.

Setting io_opt to the logical block size in the NVMe driver is
equivalent to telling the filesystems that they should not submit I/Os
larger than one sector. That makes no sense. This change is correct.

Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>

-- 
Martin K. Petersen	Oracle Linux Engineering

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  reply	other threads:[~2020-05-14  3:30 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-05-14  1:54 [PATCH] nvme: Fix io_opt limit setting Damien Le Moal
2020-05-14  3:29 ` Martin K. Petersen [this message]
2020-05-14  3:40 ` Keith Busch
2020-05-14  3:47   ` Damien Le Moal
2020-05-14  4:12     ` Keith Busch
2020-05-14  4:13       ` Damien Le Moal
2020-05-14  4:47 ` Bart Van Assche
2020-05-14  4:49   ` Damien Le Moal
2020-05-14 22:19   ` Martin K. Petersen
2020-05-14  6:11 ` Hannes Reinecke

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