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Re: [Qemu-devel] [PATCH v3 01/10] Introduce qemu_cond_timedwait for POSI
From: |
Jan Kiszka |
Subject: |
Re: [Qemu-devel] [PATCH v3 01/10] Introduce qemu_cond_timedwait for POSIX |
Date: |
Thu, 05 Apr 2012 15:24:59 +0200 |
User-agent: |
Mozilla/5.0 (X11; U; Linux i686 (x86_64); de; rv:1.8.1.12) Gecko/20080226 SUSE/2.0.0.12-1.1 Thunderbird/2.0.0.12 Mnenhy/0.7.5.666 |
On 2012-04-05 15:20, malc wrote:
> On Thu, 5 Apr 2012, Jan Kiszka wrote:
>
>> 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.
>
> The code attempts to sleep for ten seconds, which can turn into an hour
> and ten seconds if the conditions are right.
Yes, but look at what happens then: it is unlikely that the thread will
stay idle so long on a busy system (some request will wake it up earlier
again), and even if that happens, the thread will simply consume a few
resources "a bit" longer.
Jan
--
Siemens AG, Corporate Technology, CT T DE IT 1
Corporate Competence Center Embedded Linux
- Re: [Qemu-devel] [PATCH v3 01/10] Introduce qemu_cond_timedwait for POSIX, (continued)
- Re: [Qemu-devel] [PATCH v3 01/10] Introduce qemu_cond_timedwait for POSIX, Jan Kiszka, 2012/04/05
- Re: [Qemu-devel] [PATCH v3 01/10] Introduce qemu_cond_timedwait for POSIX, Peter Maydell, 2012/04/05
- Re: [Qemu-devel] [PATCH v3 01/10] Introduce qemu_cond_timedwait for POSIX, malc, 2012/04/05
- Re: [Qemu-devel] [PATCH v3 01/10] Introduce qemu_cond_timedwait for POSIX, Paolo Bonzini, 2012/04/05
- Re: [Qemu-devel] [PATCH v3 01/10] Introduce qemu_cond_timedwait for POSIX, malc, 2012/04/05
- Re: [Qemu-devel] [PATCH v3 01/10] Introduce qemu_cond_timedwait for POSIX, Paolo Bonzini, 2012/04/05
- Re: [Qemu-devel] [PATCH v3 01/10] Introduce qemu_cond_timedwait for POSIX, Jan Kiszka, 2012/04/05
- Re: [Qemu-devel] [PATCH v3 01/10] Introduce qemu_cond_timedwait for POSIX, malc, 2012/04/05
- Re: [Qemu-devel] [PATCH v3 01/10] Introduce qemu_cond_timedwait for POSIX, Jan Kiszka, 2012/04/05
- Re: [Qemu-devel] [PATCH v3 01/10] Introduce qemu_cond_timedwait for POSIX, malc, 2012/04/05
- Re: [Qemu-devel] [PATCH v3 01/10] Introduce qemu_cond_timedwait for POSIX,
Jan Kiszka <=
- Re: [Qemu-devel] [PATCH v3 01/10] Introduce qemu_cond_timedwait for POSIX, malc, 2012/04/05
- Re: [Qemu-devel] [PATCH v3 01/10] Introduce qemu_cond_timedwait for POSIX, malc, 2012/04/05
[Qemu-devel] [PATCH v3 04/10] qemu-thread: Factor out qemu_error_exit, Jan Kiszka, 2012/04/05
[Qemu-devel] [PATCH v3 03/10] Switch compatfd to QEMU thread, Jan Kiszka, 2012/04/05
[Qemu-devel] [PATCH v3 05/10] Introduce QemuEvent abstraction, Jan Kiszka, 2012/04/05
[Qemu-devel] [PATCH v3 02/10] Switch POSIX compat AIO to QEMU abstractions, Jan Kiszka, 2012/04/05
[Qemu-devel] [PATCH v3 06/10] Use QemuEvent in main loop, Jan Kiszka, 2012/04/05
[Qemu-devel] [PATCH v3 07/10] Drop unused qemu_eventfd, Jan Kiszka, 2012/04/05