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Revision ff01b9163655ace76b29b7ff2f56b25c32f795da authored by Roel Kluin on 03 February 2009, 07:19:50 UTC, committed by David S. Miller on 03 February 2009, 07:19:50 UTC 
cassini/sungem: limit reaches -1, but 0 tested
 
while (limit--)
	if (test())
		break;

if (limit <= 0)
	goto test_failed;

In the last iteration, limit is decremented after the test to 0.
If just thereafter test() succeeds and a break occurs, the goto
still occurs because limit is 0.

Signed-off-by: Roel Kluin <roel.kluin@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
1 parent 46578a6
Raw File
basic_profiling.txt 
These instructions are deliberately very basic. If you want something clever,
go read the real docs ;-) Please don't add more stuff, but feel free to 
correct my mistakes ;-)    (mbligh@aracnet.com)
Thanks to John Levon, Dave Hansen, et al. for help writing this.

<test> is the thing you're trying to measure.
Make sure you have the correct System.map / vmlinux referenced!

It is probably easiest to use "make install" for linux and hack
/sbin/installkernel to copy vmlinux to /boot, in addition to vmlinuz,
config, System.map, which are usually installed by default.

Readprofile
-----------
A recent readprofile command is needed for 2.6, such as found in util-linux
2.12a, which can be downloaded from:

http://www.kernel.org/pub/linux/utils/util-linux/

Most distributions will ship it already.

Add "profile=2" to the kernel command line.

clear		readprofile -r
		<test>
dump output	readprofile -m /boot/System.map > captured_profile

Oprofile
--------

Get the source (see Changes for required version) from
http://oprofile.sourceforge.net/ and add "idle=poll" to the kernel command
line.

Configure with CONFIG_PROFILING=y and CONFIG_OPROFILE=y & reboot on new kernel

./configure --with-kernel-support
make install

For superior results, be sure to enable the local APIC. If opreport sees
a 0Hz CPU, APIC was not on. Be aware that idle=poll may mean a performance
penalty.

One time setup:
		opcontrol --setup --vmlinux=/boot/vmlinux

clear		opcontrol --reset
start		opcontrol --start
		<test>
stop		opcontrol --stop
dump output	opreport >  output_file

To only report on the kernel, run opreport -l /boot/vmlinux > output_file

A reset is needed to clear old statistics, which survive a reboot.
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