在 2013-8-31，下午3:22，Sebastian Huber <[email protected]> 写道：
> On 2013-08-31 03:49, WeiY wrote:
>> + while (!stop(ctx)) {
>> + while (_Atomic_Compare_exchange_uint(&ctx->global_swap,
>> &ctx->global_swap_t,
>> + worker_index, ATOMIC_ORDER_ACQUIRE, ATOMIC_ORDER_RELEASE)) {
>> + /* Wait */
>> + }
>> + ++counter;
>> + ++ctx->flag_counter;
>> + ctx->global_swap_t = worker_index;
>> + }
>
> This doesn't work since ctx->global_swap_t is a normal variable. Also the
> failure memory order is wrong. You try to implement a mutex here. In case
> the compare exchange failed, then we try it again thus we don't care about a
> particular memory order here (ATOMIC_ORDER_RELAXED). The success order is
> all right, since this is the mutex acquire path.
Right, the failure memory order should use ATOMIC_ORDER_RELAXED, because when
compare exchange failed the thread of loading does not have any dependence on
other threads.
I think if i add a memory_barrier after 'ctx->global_swap_t = worker_index;' it
will be ok. Am i right?
>
>
> The init and fini handler for the test case don't fit to the body.
Yeah,
1. I should add add ctx->flag_counter = 0 to init handler.
2. In the fink handler i should also use flag_counter instead of global_uint.
> --
> Sebastian Huber, embedded brains GmbH
>
> Address : Dornierstr. 4, D-82178 Puchheim, Germany
> Phone : +49 89 189 47 41-16
> Fax : +49 89 189 47 41-09
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>
> Diese Nachricht ist keine geschäftliche Mitteilung im Sinne des EHUG.
>
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