Re: [Qemu-devel] [PATCH v3 01/10] Introduce qemu_cond_timedwait for POSIX

[Jan Kiszka <jan.kiszka@siemens.com>]

On 2012-04-05 15:00, malc wrote:
> On Thu, 5 Apr 2012, Jan Kiszka wrote:
> 
>> On 2012-04-05 14:56, Paolo Bonzini wrote:
>>> Il 05/04/2012 14:53, malc ha scritto:
>>>> On Thu, 5 Apr 2012, Paolo Bonzini wrote:
>>>>
>>>>> Il 05/04/2012 14:30, malc ha scritto:
>>>>>>>> Would save that "* 1000". I just wondered why we do not use it elsewhere
>>>>>>>> in QEMU and was reluctant to risk some BSD breakage.
>>>>>>>>
>>>>>> It's probably worth mentioning that using anything other than 
>>>>>> clock_gettime and CLOCK_MONOTONING (as well as setting proper pthread
>>>>>> clock attr on the condition variable) is prone to the surprises (such
>>>>>> as NTP corrections and daylight saving changes).
>>>>>
>>>>> I was about to suggest the same, but how widespread is support for
>>>>> pthread_condattr_setclock?
>>>>
>>>> If it's not all is lost anyway.
>>>
>>> Only once every year. :)
>>
>> ...and not for the current user of this service which do not care that
>> much about the timeout and a potential delay or early shot.
>>
> 
> An hour of potential delay mind you.

Nope, look at posix-aio-compat. It's an optimization to keep the number
worker threads under control.

Granted, time adjustments can make qemu_cond_timedwait in this primitive
(but easily portable) form less useful for other purposes.

Jan

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