On Thu, 6 Jan 2022 07:28:31 -0500, Michael S. Tsirkin <mst@xxxxxxxxxx> wrote: > On Fri, Oct 29, 2021 at 02:28:11PM +0800, Xuan Zhuo wrote: > > If the VIRTIO_RING_F_INDIRECT_DESC negotiation succeeds, and the number > > of sgs used for sending packets is greater than 1. We must constantly > > call __kmalloc/kfree to allocate/release desc. > > > So where is this going? I really like the performance boost. My concern > is that if guest spans NUMA nodes and when handler switches from > node to another this will keep reusing the cache from > the old node. A bunch of ways were suggested to address this, but > even just making the cache per numa node would help. > In fact, this is the problem I encountered in implementing virtio-net to support xdp socket. With virtqueue reset[0] has been merged into virtio spec. I am completing this series of work. My plan is: 1. virtio support advance dma 2. linux kernel/qemu support virtqueue reset 3. virtio-net support AF_XDP 4. virtio support cache indirect desc [0]: https://github.com/oasis-tcs/virtio-spec/issues/124 Thanks. > > > In the case of extremely fast package delivery, the overhead cannot be > > ignored: > > > > 27.46% [kernel] [k] virtqueue_add > > 16.66% [kernel] [k] detach_buf_split > > 16.51% [kernel] [k] virtnet_xsk_xmit > > 14.04% [kernel] [k] virtqueue_add_outbuf > > 5.18% [kernel] [k] __kmalloc > > 4.08% [kernel] [k] kfree > > 2.80% [kernel] [k] virtqueue_get_buf_ctx > > 2.22% [kernel] [k] xsk_tx_peek_desc > > 2.08% [kernel] [k] memset_erms > > 0.83% [kernel] [k] virtqueue_kick_prepare > > 0.76% [kernel] [k] virtnet_xsk_run > > 0.62% [kernel] [k] __free_old_xmit_ptr > > 0.60% [kernel] [k] vring_map_one_sg > > 0.53% [kernel] [k] native_apic_mem_write > > 0.46% [kernel] [k] sg_next > > 0.43% [kernel] [k] sg_init_table > > 0.41% [kernel] [k] kmalloc_slab > > > > This patch adds a cache function to virtio to cache these allocated indirect > > desc instead of constantly allocating and releasing desc. > > > > v3: > > pre-allocate per buffer indirect descriptors array > > > > v2: > > use struct list_head to cache the desc > > > > *** BLURB HERE *** > > > > Xuan Zhuo (3): > > virtio: cache indirect desc for split > > virtio: cache indirect desc for packed > > virtio-net: enable virtio desc cache > > > > drivers/net/virtio_net.c | 11 +++ > > drivers/virtio/virtio.c | 6 ++ > > drivers/virtio/virtio_ring.c | 131 ++++++++++++++++++++++++++++++----- > > include/linux/virtio.h | 14 ++++ > > 4 files changed, 145 insertions(+), 17 deletions(-) > > > > -- > > 2.31.0 > _______________________________________________ Virtualization mailing list Virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linuxfoundation.org/mailman/listinfo/virtualization
