[PATCH] speed up tdbbackup

[Jeremy Allison]

On Thu, Jul 23, 2015 at 09:27:49PM +0200, Volker Lendecke wrote:
> On Thu, Jul 23, 2015 at 09:09:42AM -0700, Jeremy Allison wrote:
> > On Wed, Jul 22, 2015 at 12:07:55PM +0200, Volker Lendecke wrote:
> > > Hi!
> > > 
> > > Attached find patches that speed up tdb measurably. I don't
> > > get really reliable results with "time", but I've seen up to
> > > 25% improvement on a 10-million small record tdb file on
> > > /dev/shm/. If I run a 1-million record tdbbackup, callgrind
> > > goes down from 6,916,115,142 to 4,888,697,132 instructions
> > > run. This pretty repeatable.
> > > 
> > > Now guess what patch has the larger effect... It's the
> > > tdb_oob one. I can only guess why this is the case. Probably
> > > pointer chasing is really expensive and the CPU caches are
> > > better utilized if we can call a common function.
> > > 
> > > Review&push appreciated!
> > 
> > Just fyi - looks good to me but I got an autobuild
> > fail on push, so I'll take a closer look !
> 
> Just to make sure: It did survive a private autobuild for me.

Yeah, getting a reproducible:

...tdb1-run-3G-file
tdb1-run-3G-file failed:
.Segmentation fault (core dumped)

investigating..