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List:       cygwin
Subject:    Re: does usleep() sleep more than it's supposed to?
From:       Carlo Florendo <subscribermail () gmail ! com>
Date:       2007-02-27 1:17:38
Message-ID: 45E386B2.1070506 () gmail ! com
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Lev Bishop wrote:
> On 2/26/07, Carlo Florendo  wrote:
>> I'm writing an application that requires time precisions up to the
>> microsecond level.  However, I put a hard-coded adjustment of
>> 9000 microseconds since usleep() seems to sleep on the average of
>> 9000 microseconds more than it's supposed to, at least on my
>> system.  I could work with up to 2000 microseconds for
>> function overhead but 9000 microseconds seems to be too long.
>>
>> I've attached a simple test case that let's usleep() sleep at
>> 100000 microseconds at each call.
>>
>> I've also included the output of cygcheck -svr.
>>
>> The output of the attached code on my system is the following:
> 
> FWIW, I don't see this:
> Print elapsed time at every call to usleep()
> Elapsed time (sec:microsec) 0:101000
> Elapsed time (sec:microsec) 0:100000
> Elapsed time (sec:microsec) 0:101000
> Elapsed time (sec:microsec) 0:101000
> Elapsed time (sec:microsec) 0:100000
> Elapsed time (sec:microsec) 0:101000
> Elapsed time (sec:microsec) 0:100000
> Elapsed time (sec:microsec) 0:101000
> Elapsed time (sec:microsec) 0:101000
> Elapsed time (sec:microsec) 0:100000
> 
> Print elapsed after the loop()
> Elapsed time (sec:microsec) 0:100000

Excellent! It seems your system has been tuned based on the
code sent by Brian Ford on this thread.

Thank you very much.

Best Regards,

Carlo

-- 
Carlo Florendo
Softare Engineer/Network Co-Administrator
Astra Philippines Inc.
UP-Ayala Technopark, Diliman 1101, Quezon City
Philippines
http://www.astra.ph

Member of the Astra Group of Companies
5-3-11 Sekido, Tama City
Tokyo 206-0011, Japan
http://www.astra.co.jp

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