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From: Leon Romanovsky <leon@kernel.org>
To: Max Gurtovoy <mgurtovoy@nvidia.com>
Cc: Chaitanya Kulkarni <ckulkarnilinux@gmail.com>,
	hch@infradead.org, mst@redhat.com,
	virtualization@lists.linux-foundation.org, kvm@vger.kernel.org,
	stefanha@redhat.com, israelr@nvidia.com, nitzanc@nvidia.com,
	oren@nvidia.com, linux-block@vger.kernel.org, axboe@kernel.dk
Subject: Re: [PATCH v3 1/1] virtio-blk: add num_request_queues module parameter
Date: Sun, 5 Sep 2021 13:19:18 +0300	[thread overview]
Message-ID: <YTSZpm1GZGT4BUDR@unreal> (raw)
In-Reply-To: <e4455133-ac9f-44d0-a07d-be55b336ebcc@nvidia.com>

On Sun, Sep 05, 2021 at 12:19:09PM +0300, Max Gurtovoy wrote:
> 
> On 9/5/2021 11:49 AM, Chaitanya Kulkarni wrote:
> > 
> > On 9/5/2021 12:46 AM, Leon Romanovsky wrote:
> > > > +static unsigned int num_request_queues;
> > > > +module_param_cb(num_request_queues, &queue_count_ops,
> > > > &num_request_queues,
> > > > +        0644);
> > > > +MODULE_PARM_DESC(num_request_queues,
> > > > +         "Number of request queues to use for blk device.
> > > > Should > 0");
> > > > +
> > > Won't it limit all virtio block devices to the same limit?
> > > 
> > > It is very common to see multiple virtio-blk devices on the same system
> > > and they probably need different limits.
> > > 
> > > Thanks
> > 
> > 
> > Without looking into the code, that can be done adding a configfs
> > 
> > interface and overriding a global value (module param) when it is set
> > from
> > 
> > configfs.
> > 
> > 
> You have many ways to overcome this issue.
> 
> For example:
> 
> # ls -l /sys/block/vda/mq/
> drwxr-xr-x 18 root root 0 Sep  5 12:14 0
> drwxr-xr-x 18 root root 0 Sep  5 12:14 1
> drwxr-xr-x 18 root root 0 Sep  5 12:14 2
> drwxr-xr-x 18 root root 0 Sep  5 12:14 3
> 
> # echo virtio0 > /sys/bus/virtio/drivers/virtio_blk/unbind
> 
> # echo 8 > /sys/module/virtio_blk/parameters/num_request_queues

This is global to all virtio-blk devices.

> 
> # echo virtio0 > /sys/bus/virtio/drivers/virtio_blk/bind
> 
> # ls -l /sys/block/vda/mq/
> drwxr-xr-x 10 root root 0 Sep  5 12:17 0
> drwxr-xr-x 10 root root 0 Sep  5 12:17 1
> drwxr-xr-x 10 root root 0 Sep  5 12:17 2
> drwxr-xr-x 10 root root 0 Sep  5 12:17 3
> drwxr-xr-x 10 root root 0 Sep  5 12:17 4
> drwxr-xr-x 10 root root 0 Sep  5 12:17 5
> drwxr-xr-x 10 root root 0 Sep  5 12:17 6
> drwxr-xr-x 10 root root 0 Sep  5 12:17 7
> 
> -Max.
> 
> 

  reply	other threads:[~2021-09-05 10:19 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-02 20:46 [PATCH v3 1/1] virtio-blk: add num_request_queues module parameter Max Gurtovoy
2021-09-03  6:06 ` Pankaj Gupta
2021-09-05  7:46 ` Leon Romanovsky
2021-09-05  8:49   ` Chaitanya Kulkarni
2021-09-05  9:19     ` Max Gurtovoy
2021-09-05 10:19       ` Leon Romanovsky [this message]
2021-09-05 11:16         ` Max Gurtovoy
2021-09-05 13:10           ` Leon Romanovsky
2021-09-05 13:16             ` Max Gurtovoy
2021-09-05 10:20     ` Leon Romanovsky
2021-09-05 15:15       ` Michael S. Tsirkin
2021-09-07 23:04         ` Leon Romanovsky
2021-10-22  9:30 ` Michael S. Tsirkin
2021-10-24  7:19   ` Max Gurtovoy
2021-10-24  8:12     ` Max Gurtovoy
2021-10-24  8:48       ` Michael S. Tsirkin
2021-10-24 10:57         ` Max Gurtovoy

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