Messages in this thread | | | Subject | Re: [RFC PATCH 00/11] sched: CFS low-latency features | From | Peter Zijlstra <> | Date | Fri, 27 Aug 2010 17:41:26 +0200 |
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On Fri, 2010-08-27 at 11:21 -0400, Mathieu Desnoyers wrote: > SIGEV_THREAD > Upon timer expiration, invoke sigev_notify_function as if it > were the start function of a new thread. (Among the implementa‐ > tion possibilities here are that each timer notification could > result in the creation of a new thread, or that a single thread > is created to receive all notifications.) The function is > invoked with sigev_value as its sole argument. If > sigev_notify_attributes is not NULL, it should point to a > pthread_attr_t structure that defines attributes for the new > thread (see pthread_attr_init(3). > > So basically, it's the glibc implementation that is broken, not the standard.
The standard is broken too, what context will the new thread inherit? The pthread_attr_t stuff tries to cover some of that, but pthread_attr_t doesn't cover all inherited task attributes, and allows for some very 'interesting' bugs [1].
The specification also doesn't cover the case where the handler takes more time to execute than the timer interval.
[1] - consider the case where pthread_attr_t includes the stack and we use a spawn thread on expire policy and then run into the situation where the handler is delayed past the next expiration. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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