Re: x86 clock speed patch -- Possible bug?

Nicholas J. Leon (
Sun, 2 Feb 1997 21:26:02 -0500 (EST)

On Sun, 2 Feb 1997, Stephan Meyer wrote:

# On Sat, 1 Feb 1997 wrote:
# > I have a P133. When I first started, the /proc/cpuinfo said that I had a
# > 133MHz processor. About an hour later, I look at /proc/cpuinfo from my
# > user account, and get this:
# > clock_speed : 132 MHz
# > That happened several times. Then it reverted back to:
# > clock_speed : 133 MHz
# This is definitely not a bug. On my machine, I get 119 instead of 120
# about every 20th time I read /proc/cpuinfo.
# Does your harddrive run because of some other process while doing this?

Not necessarily. The true speed is 66(external clock) x 2(multiplier) for
a total of 132. Or, if you prefer, 66.66Mhz x 2 (133.33).

It's common for programs to miscalculate the actual internal speed of a
processor. It's one of the reasons I'm surprised that it made it into the
kernel (being so hard to do and mostly innacurate). Even ctcm (a quality
low-level benchmark util) fluctuates between 131 and 134 for a P133.

Nicholas J. Leon
"Elegance through Simplicity"

"Winning could take ages, but you gotta see
your name in the high score places."