Re: [Valgrind-users] Scheduler problem

[Sefer T. <se...@ho...>]

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?

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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