[systemd-devel] kdbus performance regression by ~70% on 3.15 kernels ?

[Greg KH]

On Fri, Jun 27, 2014 at 10:19:03PM +0100, Djalal Harouni wrote:
> On Fri, Jun 27, 2014 at 12:23:05PM +0100, Djalal Harouni wrote:
> > On Fri, Jun 27, 2014 at 01:04:00PM +0200, Daniel Mack wrote:
> > > On 06/27/2014 12:51 PM, Djalal Harouni wrote:
> > > > Just to let you know that I did notice a regression by ~70% when running
> > > > test-kdbus-benchmark on a kvm guest (that's what I've under hands now)
> > > > 
> > > > I know sorry, but still a kdbus on kvm is a valid case, I don't know if
> > > > this affects real machine or only kvm guests will be able to confirm it
> > > > next week unless someone do!
> > > > 
> > > > If you are able to test it in a real machine and confirm that it affects
> > > > them too, thank you!
> > > > I've managed to bisect this to:
> > > > 3.15.0-rc1 good
> > > > 3.15.0-rc5 bad
> > > > 
> > > > I Will continue later this day!
> > > 
> > > Please do. I'm not currently aware of such a regression. What about
> > > 3.16-rc2?
> A bit late, sorry!
> 
> I was wrong on the 3.15.0-rc5 sorry that was a fedora rawhide kernel got
> confused by the naming and 'rc5'... but yes fedora rawhide affected! so
> something backported perhaps...
> 
> 
> Anyway for upstream tests:
> 
> 3.15.0-rc5 and 3.15.0-rc7 are good
> 
> 3.16-rc1 and 3.16-rc2 are bad
> 
> So I confirm there is a regression somewhere.

Can you run 'git bisect' on the kernel tree to try to track down the
problem commit?

thanks,

greg k-h