can you adjust HZ (tick rate) on Linux

[John Mannion]

Hi,

In linux kernel 2.6 the tick rate (HZ) was increased from 100ms to 1000ms.

I am curious, is it possible to adjust
this from the default and in what circumstances
might you do this ?

I recall on HP-UX that this is adjustable (but
not recommended).

Thanks

John

[Eric van Dijken]

Pros:

More frequent switching
Better interactive response

Cons:

Some hardware has problems with the clock, timewarps when coming back from disk-suspend.

I know, not much to go by..... but better than nothing.

[Steven E. Protter]

Not an area to mess around with on and important, production Linux System.

SEP

[dirk dierickx]

you can, but it is one of those params that needs to be changed in the source. although you should not have to change this unless you are running on very old equipment or some other architecture that requires this. edit the following file: /include/asm/param.h

[Florian Heigl (new acc)]

It is adjustable in the kernel source.

It's advisable in a few few cases:
- sometimes when running vmware, which iirc uses /dev/rtc.
- old bios/mainboard configs on smp systems (i.e. i have a quad ppro where threads may get kicked of the rtc they're reading by other high priority interrupts.) - in my case, linux handles the problem fine, so I didn't have to do it.
- some problems with ntp.


- possibly for real-time applications, but I do *not* know if that applies