Re: Not able to generate race condition... please help

[sandeep lahane <sandeep.lahane@xxxxxxxxx>]

On Fri, May 8, 2009 at 10:40 AM, Mulyadi Santosa <mulyadi.santosa@xxxxxxxxx> wrote:

On Fri, May 8, 2009 at 11:46 AM, mukti jain <muktijn@xxxxxxxxx> wrote:
> Hi Seshi,
>

>  I  suppose  race is generated with  LOOPCONSTANT = 100000,
>  Actually for race  on the variables the threads need to be scheduled in the
> middle of updating the variables.
>  So you should do some minimum  work  in the thread function so other
> threads get chance to run.

Uhm, could it be because it's "int"? integer, AFAIK, at least in x86
32 bit, is updated atomically.

regards,

Mulyadi.

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IMHO, you are not seeing any race since you are accessing 'volatile integers' on a non SMP machine.
AFAIK, accesses to types smaller than or equal to native pointer size are always atomic on a non SMP
machine. This is not guaranteed when multiple cores are present.

E.g.

Thread 1                      Thread 12
int count;                      count++;
count++ ;                       ---

Here count++ will always be done atomically on non SMP, but atomicity is not guaranteed when multiple cores
are present. To guarantee atomicity use atomic_t or sig_atomic_t.

CMIIW.

Regards,
Sandeep.