Name	Last modified	Size	Description
	cpucycle.java	2010-02-08 13:41	2.2K
	cpucycle-2.6.32.3.patch	2010-02-08 09:55	5.7K
	readme.txt	2005-03-08 22:38	2.2K
	cpucycle.2.6.10.patch	2005-03-08 22:13	62K

Hi,

is just uploaded my developer snapshot to the sf-webserver:

cpucycle.2.6.10.patch : apply on any recent linux kernel, you need to
  compile from scratch AFTER you have enabled cpucycle in character devices.

cpucycle.java : simple test prog in java

You wan to know, what this is:

+ This project provides a Linux 2.6 kernel patch that creates the
+ /dev/cpucycle devices that makes it possible from userspace to measure
+ the CPU-consumption (in CPU clock ticks!) in a scheduler aware
+ fashion.

still there... so what's this good for?

It's great for profiling!

 

The cpycycle concept is tested on a single CPU machine provinding results (with cpucycle.java)
with great precision. If you enable "Hyper Threading" (tm) these precision drops because
the "instruction progess/clock tick" is not constant.

The interface on /dev/cpucycle is simple, you can read 8 bytes (long long) of clock ticks
consumed by this task (process or thread) beeing scheduled. If you write a (byte)1 the output
of the filehandle changes to "network byte order" (nice in java). Reading/Writing is not buffered
so you have to read all 8 bytes in one system call or the read will fail. But because of this
it should be 100% thread safe.

The code still needs work, right not it's in a "proof of concept" state.

ToDo:
- identify correct locking on task-structs
- test on SMP machines (precision)
- don't count IRQ-handlers (maybe also not system calls)
- maybe add high precision System.currentTimeMilis in same call for fast profiling
- identify potential on other architectures

Feel free to mail me to my sf-address.

 Have fun - Leif


snippet from the kernel docs:

+	  You can compile the driver for /dev/cpucycle as a module but
+          you still need to recompile your kernel since it changes the
+          task_struct and add some code to schedule.c.
+          Automatic module loading is not supported by default, you need to
+          update your module-loading...
+          To get your /dev/cpucycle you still need to run:
+          mknod /dev/cpucycle c 10 137 ; chmod 666 /dev/cpucycle
+          (Note: the number 137 is not yet assigned officially, but
+          it was free when I last looked)