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* [PATCH bpf-next 0/4] xsk: increase NAPI budget for AF_XDP zero-copy path
@ 2020-09-07 15:02 Björn Töpel
  2020-09-07 15:02 ` [PATCH bpf-next 1/4] xsk: add XSK_NAPI_WEIGHT define Björn Töpel
                   ` (3 more replies)
  0 siblings, 4 replies; 14+ messages in thread
From: Björn Töpel @ 2020-09-07 15:02 UTC (permalink / raw)
  To: ast, daniel, netdev, bpf
  Cc: Björn Töpel, magnus.karlsson, bjorn.topel, kuba,
	intel-wired-lan

The NAPI budget (NAPI_POLL_WEIGHT), meaning the number of received
packets that are allowed to be processed for each NAPI invocation,
takes into consideration that each received packet is aimed for the
kernel networking stack.

That is not the case for the AF_XDP receive path, where the cost of
each packet is significantly less. Therefore, this commit adds a new
NAPI budget, which is the NAPI_POLL_WEIGHT scaled by 4. Typically that
would be 256 in most configuration. It is encouraged that AF_XDP
zero-copy capable drivers use the XSK_NAPI_WEIGHT, when zero-copy is
enabled.

Processing 256 packets targeted for AF_XDP is still less work than 64
(NAPI_POLL_WEIGHT) packets going to the kernel networking stack.

Jakub suggested in [1] that a more generic approach was preferred over
"driver hacks". It is arguable if adding the budget as a define which
is a scaled NAPI_POLL_WEIGHT would classify as "generic", but it is a
bit further away from "driver hacks". ;-)

The first patch adds the actual define, and last three make the Intel
drivers use it.

The AF_XDP Rx performance for "rxdrop" is up ~8% on my machine.

Routing this series via bpf-next instead of Intel Wired/netdev, since
it is a core AF_XDP addition, and hopefully Nvidia will pick this up
for the mlx5 driver.


Björn

[1] https://lore.kernel.org/netdev/20200728131512.17c41621@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com/

Björn Töpel (4):
  xsk: add XSK_NAPI_WEIGHT define
  i40e, xsk: use XSK_NAPI_WEIGHT as NAPI poll budget
  ice, xsk: use XSK_NAPI_WEIGHT as NAPI poll budget
  ixgbe, xsk: use XSK_NAPI_WEIGHT as NAPI poll budget

 drivers/net/ethernet/intel/i40e/i40e_xsk.c   | 2 +-
 drivers/net/ethernet/intel/ice/ice_xsk.c     | 2 +-
 drivers/net/ethernet/intel/ixgbe/ixgbe_xsk.c | 2 +-
 include/net/xdp_sock_drv.h                   | 3 +++
 4 files changed, 6 insertions(+), 3 deletions(-)


base-commit: bc0b5a03079bd78fb3d5cba1ccabf0a7efb1d99f
-- 
2.25.1


^ permalink raw reply	[flat|nested] 14+ messages in thread

end of thread, other threads:[~2020-09-08 20:08 UTC | newest]

Thread overview: 14+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2020-09-07 15:02 [PATCH bpf-next 0/4] xsk: increase NAPI budget for AF_XDP zero-copy path Björn Töpel
2020-09-07 15:02 ` [PATCH bpf-next 1/4] xsk: add XSK_NAPI_WEIGHT define Björn Töpel
2020-09-07 15:02 ` [PATCH bpf-next 2/4] i40e, xsk: use XSK_NAPI_WEIGHT as NAPI poll budget Björn Töpel
2020-09-07 15:02 ` [PATCH bpf-next 3/4] ice, " Björn Töpel
2020-09-07 15:02 ` [PATCH bpf-next 4/4] ixgbe, " Björn Töpel
2020-09-07 19:32   ` Jakub Kicinski
2020-09-08  5:38     ` Björn Töpel
2020-09-08  9:45   ` Eric Dumazet
2020-09-08 11:49     ` Björn Töpel
2020-09-08 15:12       ` Eric Dumazet
2020-09-08 10:12   ` [Intel-wired-lan] " Paul Menzel
2020-09-08 11:12     ` Björn Töpel
2020-09-08 11:20       ` Paul Menzel
2020-09-08 11:43         ` Björn Töpel

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