tree 2881090d0a3da1508dc51abffe358406e0527fe1
parent 184832c981fd38b1052f2dfa0262e793fa6c67d3
author Ingo Molnar <mingo@elte.hu> 1236867331 +0100
committer Sam Ravnborg <sam@ravnborg.org> 1237154527 +0100

kconfig: improve seed in randconfig

'make randconfig' uses glibc's rand function, and the seed of
that PRNG is set via:

			srand(time(NULL));

But 'time()' only increases once every second - freezing the
randconfig result within a single second.

My Nehalem testbox does randconfig much faster than 1 second
 and i have a few scripts that do 'randconfig until condition X'
loops.

Those scripts currently waste a lot of CPU time due to randconfig
changing its seed only once per second currently.

Change the seed to be micrseconds based. (I checked the statistical
spread of the seed - the now.tv_sec*now.tv_usec multiplication
there further improves it.)

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Cc: Roman Zippel <zippel@linux-m68k.org>
[sam: fix for systems where usec is zero - noticed by Geert Uytterhoeven]
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>