Michael S. Tsirkin
2021-Oct-22 09:30 UTC
[PATCH v3 1/1] virtio-blk: add num_request_queues module parameter
On Thu, Sep 02, 2021 at 11:46:22PM +0300, Max Gurtovoy wrote:> Sometimes a user would like to control the amount of request queues to > be created for a block device. For example, for limiting the memory > footprint of virtio-blk devices. > > Reviewed-by: Christoph Hellwig <hch at lst.de> > Reviewed-by: Stefan Hajnoczi <stefanha at redhat.com> > Signed-off-by: Max Gurtovoy <mgurtovoy at nvidia.com> > --- > > changes from v2: > - renamed num_io_queues to num_request_queues (from Stefan) > - added Reviewed-by signatures (from Stefan and Christoph) > > changes from v1: > - use param_set_uint_minmax (from Christoph) > - added "Should > 0" to module description > > Note: This commit apply on top of Jens's branch for-5.15/drivers > > --- > drivers/block/virtio_blk.c | 21 ++++++++++++++++++++- > 1 file changed, 20 insertions(+), 1 deletion(-) > > diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c > index 4b49df2dfd23..aaa2833a4734 100644 > --- a/drivers/block/virtio_blk.c > +++ b/drivers/block/virtio_blk.c > @@ -24,6 +24,23 @@ > /* The maximum number of sg elements that fit into a virtqueue */ > #define VIRTIO_BLK_MAX_SG_ELEMS 32768 > > +static int virtblk_queue_count_set(const char *val, > + const struct kernel_param *kp) > +{ > + return param_set_uint_minmax(val, kp, 1, nr_cpu_ids); > +} > + > +static const struct kernel_param_ops queue_count_ops = { > + .set = virtblk_queue_count_set, > + .get = param_get_uint, > +}; > + > +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"); > + > static int major; > static DEFINE_IDA(vd_index_ida); >I wasn't happy with the message here so I tweaked it. Please look at it in linux-next and confirm. Thanks!> @@ -501,7 +518,9 @@ static int init_vq(struct virtio_blk *vblk) > if (err) > num_vqs = 1; > > - num_vqs = min_t(unsigned int, nr_cpu_ids, num_vqs); > + num_vqs = min_t(unsigned int, > + min_not_zero(num_request_queues, nr_cpu_ids), > + num_vqs); > > vblk->vqs = kmalloc_array(num_vqs, sizeof(*vblk->vqs), GFP_KERNEL); > if (!vblk->vqs) > -- > 2.18.1