From: Max Gurtovoy <mgurtovoy@nvidia.com>
Date: Thu, 2 Sep 2021 23:46:22 +0300
Subject: virtio-blk: add num_request_queues module parameter
Git-commit: 0989c41bed96e5dcf7939c6303e3759f02c4c16f
Patch-mainline: v5.16-rc1
References: jsc#PED-1559
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.
[lduncan: refreshed to apply]
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Max Gurtovoy <mgurtovoy@nvidia.com>
Link: https://lore.kernel.org/r/20210902204622.54354-1-mgurtovoy@nvidia.com
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Lee Duncan <lduncan@suse.com>
---
drivers/block/virtio_blk.c | 23 ++++++++++++++++++++++-
1 file changed, 22 insertions(+), 1 deletion(-)
--- 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 *vb
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)