[PATCH] Cache messaging dgm connections

[Ralph Böhme]

On Sun, Sep 11, 2016 at 10:51:20AM -0700, Jeremy Allison wrote:
> On Sun, Sep 11, 2016 at 04:07:15PM +0200, Ralph Böhme wrote:
> > Hi!
> > 
> > Attached is a performance improvement for our dgram messaging.
> > 
> > In most cases, the current code opens a new connection to peers for
> > every message and closes it when done. This patchset adds caching of
> > connections to peers.
> > 
> > Please review & push if ok.
> 
> OK, I have to ask :-) - I'm guessing you've already tested
> this and have a good idea of how much performance improvement you
> get under load...
> 
> Care to share the numbers ?

copying the Linux kernel sources with robocopy (with /MT:16) from a
Windows client to the server, in a perf profile
messaging_send_iov_from() showed up with taken 3%. Only 0.5% was for
the sendmsg(), the rest is (un)become_root() (2.2%) and
socket+connect.

Cheerio!
-slow