On Tue, Feb 8, 2011 at 10:22 PM, Julian Edwards <[email protected]> wrote: > On Tuesday 08 February 2011 02:39:02 Robert Collins wrote: >> Mid end desktops these days are 8 way machines that should be able to >> easily do a full test run in < 60 minutes. > > Good luck with that. I've parallelised test runs using virtualisation before > and you get so much I/O contention that the overall increase in speed is only > about 10%. > > (Using two simultaneous runs on my quad-core Phenom)
I'm certainly aware that there are a bunch of of issues - and previous experiments here. One of the fairly early steps has to be generating a load profile for each test process - (python, librarian, appserver, postgresql etc). We need to then figure out answers to get enough capacity to scale. For instance, IO load can perhaps be largely addressed via running the test DB's in a ramdisk. I remember prior attempts with ramdisks having little impact - but that may can easily be accounted for if we consider that in a single threaded configuration we are not bottlenecked on IO: eliminating a non-bottleneck won't have a dramatic effect. In fact if we're sufficiently far below the IO thresholds in a single threaded test config, its plausible we wouldn't see any improvement. As a datapoint, bzr, which has parallelised its tests for some years now, scales nearly linearly - and its very IO heavy, writing GB's of data across an entire test run. If you hit the IO ceiling on a machine, it stops improving rapidly ;) -Rob _______________________________________________ Mailing list: https://launchpad.net/~launchpad-dev Post to : [email protected] Unsubscribe : https://launchpad.net/~launchpad-dev More help : https://help.launchpad.net/ListHelp
