First of all let me thank you for pointing to Vincent Oberle's APIC timer
module, I am trying to understand how the timer is hooked in it. BTW
forgive my ignorance but what is oprofile? the reason I am trying to hook
perfctr is, well let me tell you what I am trying to do here, I want to
measure time spent between a cli and the corresponding sti, I am using the
performance monitoring event CYCLES_INT_MASKED and setting the perfctr MSR
to overflow on the first cycle after a cli, this overflow will generate
PCINT from the APIC which I am programming in delivery mode NMI, here I will
take my initial TSC reading, and also program the APIC timer initial count
register to to trigger on the next clock, but this timer interrupt will be
kept pending as long as the interrupts are disabled in the system, and will
get serviced after a sti occurs, here I take my second TSC reading,
any comments?
Dinesh
----Original Message Follows----
From: John Levon <moz@compsoc.man.ac.uk>
To: Dinesh Nagpure <fatbrrain@hotmail.com>
CC: linux-kernel@vger.kernel.org
Subject: Re: hooking APIC timer doesnt work?
Date: Tue, 27 Mar 2001 12:38:01 +0100 (BST)
On Mon, 26 Mar 2001, Dinesh Nagpure wrote:
> Hello all,
> I am trying to use the LAPIC timer to generate interrupt for some kernel
> profiling work I am doing...but the timer ISR isnt invoking atall....here
is
> what I have done....
>
Have you seen Vincent Oberle's APIC timers module ? There is a link at
kernelnewbies.org
Also, what are you doing with the perfctr interrupt ? Are you aware of
perfctr and oprofile ?
john
-- "Stop telling God what to do." - Niels Bohr
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