From: Christoph Hellwig <hch@lst.de>
To: Nilay Shroff <nilay@linux.ibm.com>
Cc: linux-nvme@lists.infradead.org, hare@suse.de, kbusch@kernel.org,
hch@lst.de, sagi@grimberg.me, dwagner@suse.de, axboe@kernel.dk,
gjoyce@ibm.com
Subject: Re: [RFC PATCHv3 2/6] nvme-multipath: add support for adaptive I/O policy
Date: Wed, 29 Oct 2025 10:40:40 +0100 [thread overview]
Message-ID: <20251029094040.GC1066@lst.de> (raw)
In-Reply-To: <20251027092949.961287-3-nilay@linux.ibm.com>
On Mon, Oct 27, 2025 at 02:59:36PM +0530, Nilay Shroff wrote:
> This commit introduces a new I/O policy named "adaptive". Users can
> configure it by writing "adaptive" to "/sys/class/nvme-subsystem/nvme-
> subsystemX/iopolicy"
>
> The adaptive policy dynamically distributes I/O based on measured
> completion latency. The main idea is to calculate latency for each path,
> derive a weight, and then proportionally forward I/O according to those
> weights.
This really sounds like a lot of overhead, and really smells of all
that horrible old-school FC SAN thinking we've been carefully trying
to avoid in nvme.
What's the point here?
next prev parent reply other threads:[~2025-10-29 9:40 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-10-27 9:29 [RFC PATCHv3 0/6] nvme-multipath: introduce adaptive I/O policy Nilay Shroff
2025-10-27 9:29 ` [RFC PATCHv3 1/6] block: expose blk_stat_{enable,disable}_accounting() to drivers Nilay Shroff
2025-10-29 9:39 ` Christoph Hellwig
2025-10-29 16:40 ` Nilay Shroff
2025-10-27 9:29 ` [RFC PATCHv3 2/6] nvme-multipath: add support for adaptive I/O policy Nilay Shroff
2025-10-27 11:34 ` Hannes Reinecke
2025-10-27 12:09 ` Nilay Shroff
2025-10-29 9:40 ` Christoph Hellwig [this message]
2025-10-29 14:21 ` Nilay Shroff
2025-10-27 9:29 ` [RFC PATCHv3 3/6] nvme: add sysfs attribute adp_ewma_shift Nilay Shroff
2025-10-27 11:54 ` Hannes Reinecke
2025-10-27 9:29 ` [RFC PATCHv3 4/6] nvme: add sysfs attribute adp_weight_timeout Nilay Shroff
2025-10-27 11:54 ` Hannes Reinecke
2025-10-27 9:29 ` [RFC PATCHv3 5/6] nvme: add generic debugfs support Nilay Shroff
2025-10-27 11:55 ` Hannes Reinecke
2025-10-27 12:02 ` Nilay Shroff
2025-10-27 9:29 ` [RFC PATCHv3 6/6] nvme-multipath: add debugfs attribute for adaptive I/O policy stat Nilay Shroff
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