From 0989c41bed96e5dcf7939c6303e3759f02c4c16f Mon Sep 17 00:00:00 2001 From: Max Gurtovoy Date: Thu, 2 Sep 2021 23:46:22 +0300 Subject: virtio-blk: add num_request_queues module parameter 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 Reviewed-by: Stefan Hajnoczi Signed-off-by: Max Gurtovoy Link: https://lore.kernel.org/r/20210902204622.54354-1-mgurtovoy@nvidia.com Signed-off-by: Michael S. Tsirkin --- drivers/block/virtio_blk.c | 23 ++++++++++++++++++++++- 1 file changed, 22 insertions(+), 1 deletion(-) (limited to 'drivers/block') diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c index 6767fb709d25..a33fe0743672 100644 --- a/drivers/block/virtio_blk.c +++ b/drivers/block/virtio_blk.c @@ -30,6 +30,25 @@ #define VIRTIO_BLK_INLINE_SG_CNT 2 #endif +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, + "Limit the number of request queues to use for blk device. " + "0 for no limit. " + "Values > nr_cpu_ids truncated to nr_cpu_ids."); + static int major; static DEFINE_IDA(vd_index_ida); @@ -553,7 +572,9 @@ 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) -- cgit v1.2.3-59-g8ed1b