Michael S. Tsirkin
2021-Oct-24 08:48 UTC
[PATCH v3 1/1] virtio-blk: add num_request_queues module parameter
On Sun, Oct 24, 2021 at 11:12:26AM +0300, Max Gurtovoy wrote:> > On 10/24/2021 10:19 AM, Max Gurtovoy wrote: > > > > On 10/22/2021 12:30 PM, Michael S. Tsirkin wrote: > > > 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); > > > > +} > > > > + > > BTW, I've noticed in your new message you allow setting 0 so you might want > to change the code to > > param_set_uint_minmax(val, kp, 0, nr_cpu_ids); > > to a case a user will load the module with num_request_queues=0.Oh. So as written the default forces 1 queue? Send a patch please!> > > > +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! > > > > Looks good. > > > > > > > > > > > > > > @@ -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