From 38b50dba4704856194ac02b98e492d2349d64058 Mon Sep 17 00:00:00 2001 From: Stefano Brivio Date: Fri, 23 Apr 2021 22:22:37 +0200 Subject: passt: Spare some syscalls, add some optimisations from profiling Avoid a bunch of syscalls on forwarding paths by: - storing minimum and maximum file descriptor numbers for each protocol, fall back to SO_PROTOCOL query only on overlaps - allocating a larger receive buffer -- this can result in more coalesced packets than sendmmsg() can take (UIO_MAXIOV, i.e. 1024), so make sure we don't exceed that within a single call to protocol tap handlers - nesting the handling loop in tap_handler() in the receive loop, so that we have better chances of filling our receive buffer in fewer calls - skipping the recvfrom() in the UDP handler on EPOLLERR -- there's nothing to be done in that case and while at it: - restore the 20ms timer interval for periodic (TCP) events, I accidentally changed that to 100ms in an earlier commit - attempt using SO_ZEROCOPY for UDP -- if it's not available, sendmmsg() will succeed anyway - fix the handling of the status code from sendmmsg(), if it fails, we'll try to discard the first message, hence return 1 from the UDP handler Signed-off-by: Stefano Brivio --- tap.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'tap.c') diff --git a/tap.c b/tap.c index f8b8b4f..c11191c 100644 --- a/tap.c +++ b/tap.c @@ -37,9 +37,9 @@ int tap_send(int fd, void *data, size_t len, int flags) { uint32_t vnet_len = htonl(len); - send(fd, &vnet_len, 4, 0); + send(fd, &vnet_len, 4, MSG_DONTWAIT | MSG_NOSIGNAL); - return send(fd, data, len, flags); + return send(fd, data, len, flags | MSG_DONTWAIT | MSG_NOSIGNAL); } /** -- cgit v1.2.3