Bjoern A. Zeeb wrote:
On 23 Sep 2017, at 6:32, Stephen Hurd wrote:
Bjoern A. Zeeb wrote:
On 23 Sep 2017, at 1:35, Stephen Hurd wrote:
Author: shurd
Date: Sat Sep 23 01:35:14 2017
New Revision: 323942
URL: https://svnweb.freebsd.org/changeset/base/323942
Log:
Chain mbufs before passing to if_input()
Build a list of mbufs to pass to if_input() after LRO. Results in
12% small packet forwarding rate improvement.
forwarding seems a confusing word here..
The test was small (64 byte frames) received on one interface, then
sent out on a different one using the net.inet.ip.forwarding sysctl
(controlled via the gateway_enable setting in rc.conf).
Then this makes no sense as we don’t do LRO if forwarding is enabled
on the machine;
https://svnweb.freebsd.org/base/head/sys/netinet/tcp_lro.c?annotate=317390#l645
Basically, it changed from this:
foreach (mbuf in rx) {
if (lro && tcp_lro_rx(mbuf) == 0)
continue;
if_input(mbuf)
}
To this:
prev_mbuf = first_mbuf = NULL;
foreach (mbuf in rx) {
if (lro && tcp_lro_rx(mbuf) == 0)
continue;
if (prev_mbuf) {
prev_mbuf->m_nextpkt = mbuf;
prev_mbuf = mbuf;
}
else {
first_mbuf = prev_mbuf = mbuf;
}
}
if (first_mbuf)
if_input(first_mbuf);
So while before it called if_input() for each separate mbuf that was not
LROed, it now builds a chain of mbufs that were not LROed, and makes a
single call to if_input() with the whole chain. For cases like packet
forwarding where no packets are LROed, performance is better.
_______________________________________________
svn-src-all@freebsd.org mailing list
https://lists.freebsd.org/mailman/listinfo/svn-src-all
To unsubscribe, send any mail to "svn-src-all-unsubscr...@freebsd.org"
