From 47008bb51c3e11c187dacc17af334bdca97c2dca Mon Sep 17 00:00:00 2001 From: Xuan Zhuo Date: Tue, 29 Oct 2024 16:46:14 +0800 Subject: [PATCH] virtio_net: enable premapped mode for merge and small by default Currently, the virtio core will perform a dma operation for each buffer. Although, the same page may be operated multiple times. In premapped mod, we can perform only one dma operation for the pages of the alloc frag. This is beneficial for the iommu device. kernel command line: intel_iommu=on iommu.passthrough=0 | strict=0 | strict=1 Before | 775496pps | 428614pps After | 1109316pps | 742853pps In the 6.11, we disabled this feature because a regress [1]. Now, we fix the problem and re-enable it. [1]: http://lore.kernel.org/all/8b20cc28-45a9-4643-8e87-ba164a540c0a@oracle.com Tested-by: Darren Kenny Signed-off-by: Xuan Zhuo Acked-by: Jason Wang Signed-off-by: Paolo Abeni --- drivers/net/virtio_net.c | 15 +++++++++++++++ 1 file changed, 15 insertions(+) diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c index b82f6b8a8231..befc30b3abb1 100644 --- a/drivers/net/virtio_net.c +++ b/drivers/net/virtio_net.c @@ -6107,6 +6107,17 @@ err_ctrl: return -ENOMEM; } +static void virtnet_rq_set_premapped(struct virtnet_info *vi) +{ + int i; + + for (i = 0; i < vi->max_queue_pairs; i++) { + /* error should never happen */ + BUG_ON(virtqueue_set_dma_premapped(vi->rq[i].vq)); + vi->rq[i].do_dma = true; + } +} + static int init_vqs(struct virtnet_info *vi) { int ret; @@ -6120,6 +6131,10 @@ static int init_vqs(struct virtnet_info *vi) if (ret) goto err_free; + /* disable for big mode */ + if (!vi->big_packets || vi->mergeable_rx_bufs) + virtnet_rq_set_premapped(vi); + cpus_read_lock(); virtnet_set_affinity(vi); cpus_read_unlock(); -- 2.25.1