Re: [PATCH] Preemption Latency Measurement Tool

[Dieter Nützel]

Am Donnerstag, 20. September 2001 23:10 schrieb Robert Love:
> On Thu, 2001-09-20 at 04:21, Andrea Arcangeli wrote:
> > > You've forgotten a one liner.
> > >
> > >   #include <linux/locks.h>
> > > +#include <linux/compiler.h>
> >
> > woops, didn't trapped it because of gcc 3.0.2. thanks.
> >
> > > But this is not enough. Even with reniced artsd (-20).
> > > Some shorter hiccups (0.5~1 sec).
> >
> > I'm not familiar with the output of the latency bench, but I actually
> > read "4617" usec as the worst latency, that means 4msec, not 500/1000
> > msec.
>
> Right, the patch is returning the length preemption was unavailable
> (which is when a lock is held) in us. So it is indded 4ms.
>
> But, I think Dieter is saying he _sees_ 0.5~1s latencies (in the form of
> audio skips).  This is despite the 4ms locks being held.

Yes, that's the case. During dbench 16,32,40,48, etc...

-Dieter