>> I created a patch which changes the values of HZ to 400 and fixed
>> all places I could spot which report the jiffies value to
>> userspace. I think I caught all of them. Note that 400 is a nice
>> value, because we have to divide the values by 4 then, which the
>> gcc optimizes to shift operations, which can be done in one or two
>> cycles each and even parallelized on modern CPUs. Integer
>> divisions are slow on the ix86 (~20 cycles) and the sys_times()
>> needs four of them.
> I don't know anything about it (and my box is an Alpha for which HZ
> is 1024), but, one ignorant proposal: would it perhaps be
> worthwhile to have the HZ value higher for faster (x86) systems
> based on the target picked in make config?
> Say, your 400 for Pentium+ and 100 for 486 or lower..?
If we were going to do this, I'd suggest 400 for Pentium+, 200 for 486
and 100 for 386 class systems as being more reasonable, and still
maintaining the shift-optimisation mentioned above...
Best wishes from Riley.
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