On Mon, Nov 08, 2021 at 07:49:48PM +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. > > 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. > > v4: > 1. Only allow desc cache when VIRTIO_RING_F_INDIRECT_DESC negotiation is > successful > 2. The desc cache threshold can be set for each virtqueue > > v3: > pre-allocate per buffer indirect descriptors array
So I'm not sure why we are doing that. Did it improve anything? > v2: > use struct list_head to cache the desc > > 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 | 12 ++- > drivers/virtio/virtio_ring.c | 152 +++++++++++++++++++++++++++++++---- > include/linux/virtio.h | 17 ++++ > 3 files changed, 163 insertions(+), 18 deletions(-) > > -- > 2.31.0 _______________________________________________ Virtualization mailing list Virtualization@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/virtualization
