Re: Increasing HZ (patch for HZ > 1000)

[Jean-Marc Valin]

Just one more thing about the patch I sent. I think it addresses
something unclean in the bogomips computation. For example, in
arch/i386/kernel/cpu/proc.c, you have:

seq_printf(m, "\nbogomips\t: %lu.%02lu\n\n",
           c->loops_per_jiffy/(500000/HZ),
           (c->loops_per_jiffy/(5000/HZ)) % 100);

It's clear that for any case where 5000/HZ is not an integer, the
bogomips decimals will be wrong and if 500000/HZ isn't an integer, the
bogomips integer part will be wrong.

For example on a 2 GHz processor with a 4000 bogomips value and HZ=1200,
the code above will produce 3996.66 instead of 4000. Of course, as soon
as HZ goes above 5000, you have a divide by zero right at compile time.

	Jean-Marc

-- 
Jean-Marc Valin, M.Sc.A., ing. jr.
LABORIUS (http://www.gel.usherb.ca/laborius)
Université de Sherbrooke, Québec, Canada

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