On Wed, Dec 21, 2016 at 1:30 PM, David Miller <da...@davemloft.net>
wrote:
From: Josef Bacik <jba...@fb.com>
Date: Tue, 20 Dec 2016 15:07:01 -0500
In inet_csk_get_port we seem to be using smallest_port to figure
out where the
best place to look for a SO_REUSEPORT sk that matches with an
existing set of
SO_REUSEPORT's. However if we get to the logic
if (smallest_size != -1) {
port = smallest_port;
goto have_port;
}
we will do a useless search, because we would have already done the
inet_csk_bind_conflict for that port and it would have returned 1,
otherwise we
would have gone to found_tb and succeeded. Since this logic makes
us do yet
another trip through inet_csk_bind_conflict for a port we know
won't work just
delete this code and save us the time.
Signed-off-by: Josef Bacik <jba...@fb.com>
So the "all else being equal, use 'tb' with smallest socket count"
logic
wasn't being used at all?
Instead of removing it why don't we make it work properly again?
Something
obviously broke it somewhere along the line, because I am pretty sure
this
heuristic worked at some point in the past.
Yeah as soon as we would find a tb with no bind conflicts we'd
immediately jump to found_tb: and subsequently exit, so if we did
manage to get to the point of checking smallest_size it would be
redundant as we would have had to hit a bind conflict for that port to
even reach that code.
How do you want me to add it back? The logic only kicked in if we were
SO_REUSEPORT with snum == 0, but Tom tells me that is basically
useless, so we've disallowed that behavior. Should we call a
bind_conflict() for every port and then go back and pick the one with
the smallest tb? That's a lot of scanning. Can you tell me what
behavior you desire and I'll add another patch to reintroduce it?
Thanks,
Josef
