tcp-zerocopy: Return inq along with tcp receive zerocopy.
authorArjun Roy <arjunroy@google.com>
Fri, 14 Feb 2020 23:30:49 +0000 (15:30 -0800)
committerDavid S. Miller <davem@davemloft.net>
Mon, 17 Feb 2020 03:25:02 +0000 (19:25 -0800)
commitc8856c051454909e5059df4e81c77b9c366c5515
tree72b78bb1392b3d2209b387599d8f15fbb2fcae5c
parent8c8da5b8eaf80b9958de96cce189abd4bd1aaff1
tcp-zerocopy: Return inq along with tcp receive zerocopy.

This patchset is intended to reduce the number of extra system calls
imposed by TCP receive zerocopy. For ping-pong RPC style workloads,
this patchset has demonstrated a system call reduction of about 30%
when coupled with userspace changes.

For applications using edge-triggered epoll, returning inq along with
the result of tcp receive zerocopy could remove the need to call
recvmsg()=-EAGAIN after a successful zerocopy. Generally speaking,
since normally we would need to perform a recvmsg() call for every
successful small RPC read via TCP receive zerocopy, returning inq can
reduce the number of system calls performed by approximately half.

Signed-off-by: Arjun Roy <arjunroy@google.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Soheil Hassas Yeganeh <soheil@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
include/uapi/linux/tcp.h
net/ipv4/tcp.c