Re: Illegal use of reserved word in system.h

[Ben Greear <greearb@candelatech.com>]

Lee Revell wrote:
> On Fri, 2005-05-20 at 11:27 +0200, Helge Hafting wrote:
> 
>>Ben Greear wrote:
>>
>>
>>>Arjan van de Ven wrote:
>>>
>>>
>>>>HZ may not exist. At all; people are trying to remove it. And userspace
>>>>has no business knowing about it either.
>>>
>>>
>>>It can be helpful to know what HZ you are running at, for instance if 
>>>you care
>>>very much about the (average) precision of a select/poll timeout.
>>>
>>
>>Will  knowing it help?  You may find out that you don't have much precision,
>>but then theres nothing to do about it.
> 
> 
> Yes, it will.  If you have an RT constraint and 10ms won't cut it (say,
> you want to send MIDI clock) then you can use the RTC.

Right.  For instance, before I found the 1000 HZ patch for the 2.4
kernel I would set the RTC to tick 1024 times a second, and then add
that FD to my select() fd-sets.  That causes select to return after about
1ms, and I could do this in a loop to get the X ms of sleep that I needed.

This is not as nice as having a clean 1ms tick clock, but it's a hell of
a lot better than a full busy spin...

Ben

-- 
Ben Greear <greearb@candelatech.com>
Candela Technologies Inc  http://www.candelatech.com