lkml.org 
[lkml]   [2003]   [Dec]   [12]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: Increasing HZ (patch for HZ > 1000)
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
[unhandled content-type:application/pgp-signature]
\
 
 \ /
  Last update: 2005-03-22 13:59    [W:0.060 / U:4.220 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site