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Re: Semperon processors



On Sun, 2005-01-30 at 02:26 -0300, Alexandre Strube wrote:
> Em SÃb, 2005-01-29 Ãs 10:55 -0500, Matthew Miller escreveu:
> > On Sat, Jan 29, 2005 at 07:41:29AM -0300, Alexandre Strube wrote:
> > > What they used to do was set the instruction halt (or something alike)
> > > when the processor was idle. Having setiathome running forever will make
> > > those softcoolers only a waste of memory.
> > > I don't know what could be changed so fedora don't have this.
> > 
> > HZ is now 1000 instead of 100. This means the CPU is woken up 10 times more
> > often from its halted state.
> 
> Why?

the theory seems to be that HZ=1000 gives a better interactive response.
(you can measure a lot of things better with a 1ms sample period than
with a 10ms sample period). Another reason is that with HZ=1000
userspace can sleep more accurate intervals, which is especially helpful
for video playback (if the least you can sleep is 20ms, doing 60Hz
playback sucks, but if you can do 2ms in 1ms increments you get a lot
better)

I'm not so convinced either way to be honest; for a while I had HZ=100
patched into the kernel, but people complained so I set it back to 1000
way back. Now that I have a laptop with powersaving I think I'll build
myself a kernel with HZ=100 again.

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