[0/3] virtio support cache indirect desc

Message

Xuan Zhuo Oct. 27, 2021, 6:19 a.m. UTC

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.


Xuan Zhuo (3):
  virtio: cache indirect desc for split
  virtio: cache indirect desc for packed
  virtio-net: enable virtio indirect cache

 drivers/net/virtio_net.c     |   4 ++
 drivers/virtio/virtio.c      |   6 ++
 drivers/virtio/virtio_ring.c | 120 ++++++++++++++++++++++++++++++-----
 include/linux/virtio.h       |  10 +++
 4 files changed, 123 insertions(+), 17 deletions(-)

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2.31.0