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From Ian Holsman <>
Subject Re: [PATCH] fix scoreboard state for worker threads
Date Wed, 19 Sep 2001 16:48:49 GMT
On Wed, 2001-09-19 at 08:39, Justin Erenkrantz wrote:
> On Wed, Sep 19, 2001 at 02:51:11AM -0700, Brian Pane wrote:
> > I think it's reasonable to assume that Solaris will make smart decisions
> > about LWP locality.  If you want to validate this assumption empirically,
> > though, I think it's possible to get a snapshot of what CPU is running
> > each LWP, via Solaris-specific ioctls on the corresponding /proc file.
> > (I know this was possible in 5.6; it's probably still supported in 5.8.)
> Yeah, I was purposely not playing with any CPU monitoring tools while
> it was running as I didn't want to disturb the results.  I may run the
> tests again tonight (or this weekend if I can't get to it tonight -
> I'm moving tomorrow) and watch it with the /usr/proc/bin/p* files - I 
> won't be paying attention to the rps this time, but the CPU performance.
> > This issue, by the way, makes me favor letting the OS figure out the
> > thread concurrency for itself: assuming that the number of child processes
> > is greater than or equal to the number of CPUs, it might be more effective
> > to have a small number of LWPs per process, with a large number of threads
> > per LWP for cache locality purposes.
> ++1.  =-)
> > >- Justin mentioned that he observed much higher load on the worker tests
> > >  compared to the prefork tests. Something on the order of ~8 for the
> > >  worker case, and ~3-4 for prefork was discussed. Can someone explain
> > >  to us why this might be happening? It obviously didn't impact
> > >  performance negatively, since the worker performed slightly better.
> > >
> > 
> > I'm surprised about this result.  In Ian's tests comparing worker and
> > prefork on an 8-CPU Solaris box, the load average was about the same
> > for both MPMs.  Justin, do you remember how the usr+sys CPU utilization
> > for worker compared to that of prefork in your test?
> Actually, I think the CPU utilization was less with worker, but the
> load was much higher.  I have no clue how that is.  When I run it 
> again, I'll keep an eye out for these values.  -- justin

Worker (for me) had very high mutex contention
also.. can you make sure your not maxing out your network card
(like I did)


Ian Holsman
Performance Measurement & Analysis
CNET Networks   -   (415) 364-8608

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