Re: [Valgrind-users] Scheduler problem

[Julian S. <js...@ac...>]

On Wednesday 09 April 2003 7:17 am, Sefer Tov wrote:
> Indeed, you were both correct.
> I am running it on a laptop (compaq armada m300) with apm enabled.
>
> I must admit that this proves to be quite an annoyance, since I do most of
> my work on a laptop. Does that affect the timing of other functions as
> well?
>
> I'm unfailiar with these high resolution time counters in x86, but it
> strikes me odd that Intel wouldn't provide an equivilant, reliable
> mechanism for laptops as well (maybe in exchange of accuracy or slight
> performance impact).
>
> I'm curious, is there any way around this?

Try the patch called 09-rdtsc-calibration from
http://www.goop.org/~jeremy/valgrind/

J


>
> Thanks in advance,
>     Sefer.
>
>
> From: Julian Seward <js...@ac...>
>
> >To: Jeremy Fitzhardinge <je...@go...>, Sefer Tov <se...@ho...>
> >CC: val...@li...
> >Subject: Re: [Valgrind-users] Scheduler problem
> >Date: Tue, 8 Apr 2003 21:24:24 +0000
> >
> >
> >Sefer,
> >
> >I tested the program you sent me (below) and it behaves
> >identically running on V from normal; no timing anomalies.
> >This is running on a 1133Mhz PIII-T (desktop) machine.
> >
> >I suspect Jeremy may be right about the power management thing;
> >he's had a patch available for that for a while.  Can you
> >clarify the situation re power management on your platform?
> >Thanks.
> >
> >J
> >
> >#include <pthread.h>
> >#include <stdio.h>
> >#include <unistd.h>
> >
> >
> >void *start(void *p)
> >{
> >         printf("Hi!\n");
> >         sleep(1);
> >         printf("Here\n");
> >         sleep(1);
> >
> >         return 0;
> >}
> >
> >
> >int main()
> >{
> >         pthread_t tid;
> >         void *p;
> >         int i;
> >
> >         for ( i = 0; i < 5; ++i ) {
> >                 pthread_create(&tid, 0, start, 0);
> >         }
> >         pthread_join(tid, &p);
> >
> >         return 0;
> >}
> >
> >On Tuesday 08 April 2003 10:12 am, Jeremy Fitzhardinge wrote:
> > > Quoting Sefer Tov <se...@ho...>:
> > > > Hi!
> > > >
> > > > I've been testing a short threaded program, and I noticed that
> >
> >sleep(x),
> >
> > > > although utilizes no cpu, it schdules poorly (the program slows down
> > > > almost
> > > > to a halt).
> > >
> > > Is your machine a laptop, or a desktop with power management enabled?
> > > Valgrind uses the TSC register as its timebase, and I've noticed on my
> > > laptop the TSC doesn't advance when the machine is idle.  You can
> > > easily tell if this is the case: if you run a CPU-bound program at the
> > > same
> >
> >time,
> >
> > > then the TSC advances at near full speed and the sleeps are for the
> >
> >right
> >
> > > time.
> > >
> > > 	J
>
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