Re: What's the timeslice size for kernel 2.6.0-test2, IA32?

From: george anzinger (george@mvista.com)
Date: Sat Aug 02 2003 - 04:25:52 EST


Ben Greear wrote:
>
> Mark Mielke wrote:
>
>> On Fri, Aug 01, 2003 at 02:04:46PM -0230, Stephen Anthony wrote:
>>
>>> It would be great if sleeps were 1ms accurate instead of 10ms. It
>>> would make synchronization code a lot easier.
>>
>>
>>
>> Doesn't this depend on what HZ you define for the kernel?
>>
>> If you want 1ms sleep, just set HZ to 1000HZ+, and give your process a
>> high priority?

As it currently stands in the 2.6 kernel for the i386, HZ is defined
as 1000. Since the PIT interrupt source can not hit this, the actual
timer interrupt period is 999848 nano seconds. The minimum sleep
interval nanosleep will take is 1 of these and since the time may
start between ticks it adds another to give a min sleep time of
999848+~1/2 of that depending on where the request falls in the time
period.

-- 
George Anzinger   george@mvista.com
High-res-timers:  http://sourceforge.net/projects/high-res-timers/
Preemption patch: http://www.kernel.org/pub/linux/kernel/people/rml

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