This is from mobile so I can not look at code much but if you are
converting nanoseconds to milliseconds you multiply by 1e6 not 1e-6 I
think.
Ron
On 3/22/09, cinap_len...@gmx.de <cinap_len...@gmx.de> wrote:
> This is actualy very interesting. Riped the parts from periodic.c
> to play a with the code to see how it reacts to some changes.
>
> The code below reproduces the problem:
>
> sleep()+0x7 /sys/src/libc/9syscall/sleep.s:5
> periodicThread(msec=0x3e8)+0xb2 /tmp/a.c:21
> ct=0x47a68e5b
> t=0x47e50e4d
> ts=0x0
> main()+0x10 /tmp/a.c:32
> _main+0x31 /sys/src/libc/386/main9.s:16
>
>
> The zerosleeps go away if one uncomments the foo print. It also
> goes away if one makes the sleep one milli second longer by
> changing ts to ts+1.
>
> I would love if anybody gives a good explaination of this bug
> and how to fix it :-)
>
> #include <u.h>
> #include <libc.h>
>
> static void
> periodicThread(int msec)
> {
> double t, ct, ts;
>
> ct = nsec()*1e-6;
> t = ct + msec;
>
> for(;;){
> /* skip missed */
> while(t <= ct)
> t += msec;
>
> ts = t - ct;
> if(ts > 1000)
> ts = 1000;
> sleep(ts);
> ct = nsec()*1e-6;
> if(t <= ct){
> // print("foo!\n");
> t += msec;
> }
> }
> }
>
> void
> main(int argc, char *argv[])
> {
> periodicThread(1000);
> }
>
--
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