Re: Interactivity regression since v3.11 in mm/vmscan.c

From: Felipe Contreras
Date: Mon Jun 09 2014 - 06:02:48 EST


Michal Hocko wrote:
> On Fri 06-06-14 18:11:14, Felipe Contreras wrote:
> > On Fri, Jun 6, 2014 at 5:33 AM, Felipe Contreras
> > <felipe.contreras@xxxxxxxxx> wrote:
> > > On Fri, Jun 6, 2014 at 4:16 AM, Michal Hocko <mhocko@xxxxxxx> wrote:
> > >
> > >> Mel has a nice systemtap script (attached) to watch for stalls. Maybe
> > >> you can give it a try?
> > >
> > > Is there any special configurations I should enable?
> > >
> > > I get this:
> > > semantic error: unresolved arity-1 global array name, missing global
> > > declaration?: identifier 'name' at /tmp/stapd6pu9A:4:2
> > > source: name[t]=execname()
> > > ^
> > >
> > > Pass 2: analysis failed. [man error::pass2]
> > > Number of similar error messages suppressed: 71.
> > > Rerun with -v to see them.
> > > Unexpected exit of STAP script at
> > > /home/felipec/Downloads/watch-dstate-new.pl line 320.
> >
> > Actually I debugged the problem, and it's that the format of the
> > script is DOS, not UNIX. After changing the format the script works.
>
> Ups, I've downloaded it from our bugzilla so maybe it just did some
> tricks with the script.
>
> > However, it's not returning anything. It's running, but doesn't seem
> > to find any stalls.
>
> Intereting. It was quite good at pointing at stalls. How are you
> measuring those stalls during your testing?

I'm not measuring them, I simply grab a GUI window and move it around
while the big file is being copied, when the issue happens the window
stops moving, and the mouse, everything hangs for a time, then it
resumes, then hangs again... the interactivity is bad.

--
Felipe Contreras
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