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List:       redhat-devel
Subject:    RE: Interrupt frequency
From:       "Rokicki, Andrew" <ARokicki () US ! TIAuto ! com>
Date:       2004-08-31 12:21:57
Message-ID: 076E02306E643D44B349985C46E78040057F3E () mrdex00 ! na ! tiauto ! com
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> If I change the HZ value from 100 to 1000 can I get more precision ?
> 
> What are the things affected ? (I know one thing the 'uptime' is
> affected since it keeps time in jiffies)
> 
If you change HZ from 100 to 1000 you will get task slice of 1ms.
This means that a process will run for 1ms before it gives up the CPU. 
On our systems I changed HZ to 4096 this gives a slice time of  0.25ms( you
have to do minor modifications to some other files to go that low 1000
should be fine.)
I have not seen any problems and uptime seems to be accurate. 

The systems we use are robotic equipment so we don't do a lot other than
running the machine.
We needed small slice time to drive stepper motors.





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