From: hedrick@geneva.rutgers.edu (Charles Hedrick) Subject: Re: BogoMips??? Date: 29 Jul 1993 08:08:25 GMT
erc@apple.com (Ed Carp) writes:
>I noticed this when I booted 0.99.11 - what in the world is BogoMips and
>what does calibrate_delay do?
Various device-level code needs to wait for small periods of time for
a device to finish something. Commonly this is done by a small delay
loop. The problem is that since machines are different speeds, the
number of times you have to go through the loop to get a given delay
is different for different machines. The startup code measures the
number of loops per second, which is then used as a conversion factor
by udelay (a routine that delays a specified number of microseconds).
If I am reading the code correctly, I believe BogoMips is roughly
speaking the number of times through the loop in one second, except
that it could be off by a factor of as much as 2. I hope it's
intended as a debugging aid for Linus, to make sure the values are
reasonable on different machines, not as a way to figure out your
actual hardware speed.