From: Christoph Hellwig <hch@infradead.org>
To: Max Gurtovoy <maxg@mellanox.com>
Cc: Jens Axboe <axboe@kernel.dk>, Weiping Zhang <zwp10758@gmail.com>,
Weiping Zhang <zhangweiping@didiglobal.com>,
linux-nvme@lists.infradead.org,
Christoph Hellwig <hch@infradead.org>,
Keith Busch <kbusch@kernel.org>,
sagi@grimberg.me
Subject: Re: [PATCH] nvme: align io queue count with allocted nvme_queue in nvme_probe
Date: Wed, 22 Apr 2020 01:37:47 -0700 [thread overview]
Message-ID: <20200422083747.GA26915@infradead.org> (raw)
In-Reply-To: <df0fa3a0-7764-bc1f-711d-d264fc4f444f@mellanox.com>
On Tue, Apr 14, 2020 at 03:59:12PM +0300, Max Gurtovoy wrote:
> > > write_queues and poll queues shouldn't be writable IMO.
> > >
> > I think we can keep it writeable, the user case is that setup as many io
> > queues as possible when load nvme module, then change queue count
> > for each tag set map dynamically.
>
> We can keep it writable but I prefer not change the controller initial queue
> count after reset controller operation.
>
> So we can keep dev->write_queues and dev->poll_queues count for that.
>
> You can use the writable param in case you aim to hotplug a new device and
> you want it to probe with less/more queues.
>
> IMO this feature should've somehow configured using nvme-cli as we do with
> fabrics controllers that we never change this values after initial
> connection.
>
> Keith/Christoph,
>
> what is the right approach in your opinion ?
The problem with PCIe is that we only have a per-controller interface
once the controller is probed. So a global paramter that can be
changed, but only is sampled once at probe time seems the easiest to
me. We could also allow a per-controller sysfs file that only takes
effect after a reset, which seems a little nicer, but adds a lot of
boilerplate for just being a little nicer, so I'm not entirely sure
if it is worth the effort.
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next prev parent reply other threads:[~2020-04-22 8:37 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-10 9:57 [PATCH] nvme: align io queue count with allocted nvme_queue in nvme_probe Weiping Zhang
2020-04-12 12:38 ` Max Gurtovoy
2020-04-13 1:01 ` Weiping Zhang
2020-04-13 9:37 ` Max Gurtovoy
2020-04-13 12:00 ` Weiping Zhang
2020-04-14 12:59 ` Max Gurtovoy
2020-04-22 8:37 ` Christoph Hellwig [this message]
2020-04-22 9:24 ` weiping zhang
2020-04-22 16:57 ` Christoph Hellwig
2020-04-23 7:59 ` Weiping Zhang
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