RE: How to get CPU cycles per sec?
RE: How to get CPU cycles per sec?
- Subject: RE: How to get CPU cycles per sec?
- From: "Lalit Chandivade" <email@hidden>
- Date: Thu, 29 Jul 2004 20:28:27 +0530
It looks like the value comes from gPEClockFrequencyInfo.cpu_frequency_hz.
Is the value returned by clock_get_uptime() related with
gPEClockFrequencyInfo.cpu_frequency_hz?
For example if I want to measure 20 secs in terms of CPU cycles then can I
say
clock_get_uptime(current_time)
reuired_time = current_time + 20 * gPEClockFrequencyInfo.cpu_frequency_hz;
Will current_time be greater than or equal to required time after 20 sec?
Thanks
Lalit.
-----Original Message-----
From: email@hidden
[
mailto:email@hidden]On Behalf Of Paul Ripke
Sent: Sunday, July 25, 2004 6:02 PM
To: Lalit Chandivade
Cc: email@hidden
Subject: Re: How to get CPU cycles per sec?
On Sunday, Jul 25, 2004, at 00:08 Australia/Sydney, Lalit Chandivade
wrote:
>
Hi
>
>
As per the following discussion
>
http://lists.apple.com/archives/darwin-kernel/2004/Mar/31/
>
gettingsystemperfo
>
rmance.001.txt
>
>
clock_get_uptime gives system up time in CPU cycles.
>
Is there a way in kernel or IOKit to know the CPU cycles per second?
A little digging through xnu source should show where this is coming
from:
pbg3:ksh$ sysctl hw.cpufrequency
hw.cpufrequency = 300000000
Cheers,
--
Paul Ripke
Unix/OpenVMS/TSM/DBA
I love deadlines. I like the whooshing sound they make as they fly by.
-- Douglas Adams
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