Commit 32d18ab1 authored Oct 24, 2017 by Paolo Abeni Committed by David S. Miller Oct 27, 2017

net: updating dst lastusage is an unlikely event.



Since commit 0da4af00 ("ipv6: only update __use and lastusetime
once per jiffy at most"), updating the dst lastuse field is an
unlikely action: it happens at most once per jiffy, out of
potentially millions of calls per second.

Mark explicitly the code as such, and let the compiler generate
better code.

Note: gcc 7.2 and several older versions do actually generate
different - better - code when the unlikely() hint is in place,
avoid jump in the fast path and keeping better code locality.

Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

parent a4484705

include/net/dst.h

+1 −1

Original line number	Diff line number	Diff line
		@@ -257,7 +257,7 @@ static inline void dst_hold(struct dst_entry *dst)

		static inline void dst_use_noref(struct dst_entry *dst, unsigned long time)
		{
		if (time != dst->lastuse) {
		if (unlikely(time != dst->lastuse)) {
		dst->__use++;
		dst->lastuse = time;
		}