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From: Christoph Hellwig <hch@lst.de>
To: Daniel Wagner <dwagner@suse.de>
Cc: linux-nvme@lists.infradead.org, linux-kernel@vger.kernel.org,
	Keith Busch <kbusch@kernel.org>, Christoph Hellwig <hch@lst.de>,
	Sagi Grimberg <sagi@grimberg.me>, Hannes Reinecke <hare@suse.de>
Subject: Re: [PATCH v3 3/4] nvme: move ns id info to struct nvme_ns_head
Date: Wed, 6 Dec 2023 09:54:36 +0100	[thread overview]
Message-ID: <20231206085436.GB24484@lst.de> (raw)
In-Reply-To: <20231206081244.32733-4-dwagner@suse.de>

On Wed, Dec 06, 2023 at 09:12:43AM +0100, Daniel Wagner wrote:
> Move the namesapce info to struct nvme_ns_head, because it's the same
> for all associated namespaces.
> 
> The head pointer is accessible from the ns pointer so we could just
> update all places with ns->x to ns->head->x. While this is okay for the
> slow path,

Do you have any data to show that it matters?  All the I/O command
setup functions already access the ns_head for ->ns_id, so looking
at more fields can't really make any difference.

If we have a good argument about reducing the pointer chasing I'm all
for it, but please as a separate, well-documented commit that also
explains the tradeoffs for the newly added lookups this adds in a few
places.


  reply	other threads:[~2023-12-06  8:54 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-12-06  8:12 [PATCH v3 0/4] nvme: add csi, ms and nuse to sysfs Daniel Wagner
2023-12-06  8:12 ` [PATCH v3 1/4] nvme: lookup ctrl from request instead from namespace Daniel Wagner
2023-12-06  8:12 ` [PATCH v3 2/4] nvme: initialize head before namespace Daniel Wagner
2023-12-06  8:50   ` Christoph Hellwig
2023-12-06  8:12 ` [PATCH v3 3/4] nvme: move ns id info to struct nvme_ns_head Daniel Wagner
2023-12-06  8:54   ` Christoph Hellwig [this message]
2023-12-07 10:53     ` Daniel Wagner
2023-12-06 17:38   ` kernel test robot
2023-12-06 17:38   ` kernel test robot
2023-12-07  5:36   ` Dan Carpenter
2023-12-06  8:12 ` [PATCH v3 4/4] nvme: add csi, ms and nuse to sysfs Daniel Wagner
2023-12-06  8:59   ` Christoph Hellwig

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