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SubjectRe: Can and should the kernel HZ value be changed?
Date
On 5 Jan 1999, MOLNAR Ingo wrote:

> could you elaborate why it makes a difference?

Pretty basal stuff, really: The more often you can switch context, the
quicker the response will be for any given process residing down on the ready
list somewhere. The is pretty vital for any real-timeish application, and
nicely visualized and obvious (as well as gratifying for ones sanity) when
running X.

The compromise re. increasing HZ too much is of course that the proportion of
time spent for timer interrupt and context switch should not be too large.

And, with the 32 bit jiffies used for i386, also the problem of roll-over
becoming more pronounced. This can be handled, for instance by making
jiffies long long (at a cost) or by implementing a jiffy overflow counter
applicable for jiffiestotimespec, sysinfo uptime and such.

But all of this is definitely 2.3 stuff anyway...

Egil
--
Email: egil@kvaleberg.no Voice: +47 22523641, 92022870 Fax: +47 22525899
Snail: Egil Kvaleberg, Husebybakken 14A, 0379 Oslo, Norway
URL: http://www.kvaleberg.no/


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