[Asterisk-Users] Interrupt latency problems

[Juan J. Sierralta P.]

Hi,

      Maybe vmstat(8) could be of help instead of the so flamed top(1).

 
> > Steven Critchfield wrote:
> >
> > > top will only report userspace problems, and to top it off, top only
> > > reports on snapshots of the system on as low as 1 second. With Zap
> > > hardware hitting the system 1000 times a second for service, you might
> > > happen to get an occasional hit time here top and the hardware hit
> > > pretty close to show extra load. top also has the problem of effecting
> > > the system it is watching. It is a lot like those pesky physics problems
> > > where what you use to measure changes the object your measuring.
> > >
> > > Basically all that is to say that top probably won't tell you what you
> > > want to know.About the only thing that would be of interest is if the
> > > percentage is viewed in the system or userspace portions. If in system,
> > > you will have to go debugging the kernel.
> > >
> > > Of course, it seems this is mostly being reported against RH and FC.
> > > I'll take a quick guess that it isn't bad users so it would leave you
> > > with bad kernels. My personal opinion is to not trust what the distros
> > > do to the kernels. Even in my beloved Debian I don't trust the default
> > > kernel. I suggest you download a stock vanila kernel from kernel.org and
> > > config it as minimally as possible for your hardware and try and see if
> > > it reproduces the problems you are seeing currently.
> > >
> >
> > In line #3 (CPU) of top, I'm seeing idle time go from 100% to +/-30%
> > every 10 seconds.
> 
> So again, idle isn't helpfull. Where that time is being spent is the
> important part of the details. If it is in system, then it is IO calls
> or something else inside the kernel itself. If it is in user, then it is
> a userspace app that is getting hit every so often doing damage.
> 
> To give a bit more explicit example, if you have a perl app that wakes
> up every 10 seconds or so from a sleep to do some directory managment,
> then you would see user percentage spike at that point. However if you
> had something dump a large chunk of data to the drives, the kernel would
> slurp that data in really quick and then churn on it a moment trying to
> get it down to the filesystem. This would show itself as a system time.
> If your drive was particularly slow, it very well may hang the interupts
> for a moment as it tries to do something.
> 
> Old S3 video cards under windows used to be really bad about holding
> interupts too long. Used to be if you wiggled the mouse you could hear
> the effects in any music you happened to be playing.
> --
> Steven Critchfield <critch at basesys.com>

-- 
Juanjo sin .sig :(