System Tap - Revision history

Peter Huewe: /* Links */

2012-04-14T01:35:41Z

‎Links

Peter Huewe: Added videos

2012-04-14T01:35:20Z

Added videos

Adushistova at 10:04, 27 October 2011

2011-10-27T10:04:51Z

Jayabharath: /* See Also */

2010-04-19T15:47:38Z

‎See Also

Wmat: Fixing broken links and missing uploads.

2010-01-26T18:04:35Z

Fixing broken links and missing uploads.

TimBird: Remove CELF-isms

2007-07-06T17:03:19Z

Remove CELF-isms

RBot: Bot (Edward's framework)

2007-03-06T03:37:42Z

Bot (Edward's framework)

New page

Table Of Contents:

This page has information about [[System Tap]], which is of interest to CE Linux Forum members,
because tracers are a useful tool for CE product developers.

== Introduction ==
SystemTap is a flexible and extensible system for adding trace collection and
analysis to a running Linux kernel.

SystemTap is designed to be very flexible (allowing for the insertion of
arbitrary C code), yet also easy-to-use (most trace statements are written
in a simple scripting language, with useful data collection and aggregation
routines available in (essentially) library form).

A key aspect of SystemTap is that it is intended to allow you to create
a trace set (a "tapset"), and run it on a running Linux system, with
no modification or re-compilation of the system required. To do this, it
uses the kernel [[KProbes]] interface and loadable kernel modules to dynamically
add probe points and newly generated code to the running kernel.

== Open Source Projects/Mailing Lists ==
The main SystemTap site is at: http://sourceware.org/systemtap/

The SystemTap mail list archives are at: http://sourceware.org/ml/systemtap/

The tutorial, which gives a good overview of the system, is at:
http://sourceware.org/systemtap/tutorial/

== Miscellaneous notes ==
=== Probe types ===
There are several types of probes:
* kprobe & kretprobe, for dynamically insterted probes
* timers
* static instrumentation markers
* performance counter events

In the future, there may be:
* user-space probes,
* user-space return probes, and
* watchpoint probes (kernel & user)
* and more

== See Also ==
Note that SystemTap is one of the major tracing systems for the Linux kernel.

There is work afoot (as of spring 2006) to try to collaborate on different
parts of the tracing problem, between some of the major tracing projects.
See the [[Tracing Collaboration Project]] page for more information.

== Some Performance measurements ==
Jian Gui writes (in July 2006 on the [[System Tap]] mailing list):

<pre>
Hi, we've tested the overhead of systemtap/LKET with some benchmarks
on a ppc64 machine.

It shows the overhead of systemtap/LKET is acceptable generally.
But it will also cause significant overhead for some benchmark of
special behavior, e.g. dbench. Dbench calls kill() in a very high
frequency to check whether a task is complete, thus leads to a high
overhead.

We categorized the event hooks into five groups in the testing:
grp1 - syscall.entry, process
grp2 - syscall.return, process
grp3 - iosyscall, ioscheduler, scsi, aio, process
grp4 - tskdispatch, pagefault, netdev, process
grp5 - syscall.entry, syscall.return, process

All the results are
(score1 - score2)/score2 * 100%, where:
score1: the benchmark score when probed by systemtap
score2: the benchmark score without probing

dbench (<3% is noise)
--------------------
grp1 -14.4%
grp2 -33.1%
grp3 -7.92%
grp4 -13.6%
grp5 -43.3%

specjbb (<3% is noise)
---------------------
grp 1 -0.87%
grp 2 -0.67%
grp 4 +0.47%
grp 5 +0.05%

tiobench (<3% is noise)
----------------------
grp1 sequential reads +1.45%
sequential writes -6.98%
random reads +0.57%
random writes -2.11%
grp2 sequential reads +0.11%
sequential writes -5.81%
random reads +0.03%
random writes -2.11%
grp3 sequential reads +1.42%
sequential writes -6.98%
random reads +0.51%
random writes -2.11%
grp4 sequential reads +1.38%
sequential writes -5.81%
random reads +0.60%
random writes -2.11%
grp5 sequential reads +0.22%
sequential writes -8.14%
random reads -0.10%
random writes -1.05%

Rawiobench (<3% is noise)
------------------------
grp1 sequential aioread() 0%
sequential aiowrite() 0%
random aioread() 0%
random aiowrite() 0%
grp2 sequential aioread() 0%
sequential aiowrite() 0%
random aioread() 0%
random aiowrite() -0.82%
grp3 sequential aioread() 0%
sequential aiowrite() 0%
random aioread() 0%
random aiowrite() 0%
grp4 sequential aioread() 0%
sequential aiowrite() 0%
random aioread() +0.79%
random aiowrite() -0.82%
grp5 sequential aioread() 0%
sequential aiowrite() -6.41%
random aioread() +0.79%
random aiowrite() 0%

Test environment:
Machine: Open Power 720/ 8 cpus/ 2 cores/ 6GB RAM (tiobench use 1G)
Software: RHEL4-U3GA/ 2.6.17.2/ systemtap-20060718/ elfutils-0.122-0.4

</pre>

@@ Line 142: / Line 142: @@
 == Links ==
-* [https://events.linuxfoundation.org/events/collaboration-summit/stone SystemTap Sans Kernel: A Pure Userspace Backend]    [https://events.linuxfoundation.org/images/stories/pdf/lfcs2012_jstone.pdf Slides][http://video.linux.com/videos/systemtap-sans-kernel-a-pure-userspace-backend Video]
+* [https://events.linuxfoundation.org/events/collaboration-summit/stone SystemTap Sans Kernel: A Pure Userspace Backend]    [https://events.linuxfoundation.org/images/stories/pdf/lfcs2012_jstone.pdf Slides] [http://video.linux.com/videos/systemtap-sans-kernel-a-pure-userspace-backend Video]
 [[Category:Development Tools]]

← Older revision		Revision as of 01:35, 14 April 2012
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	</pre>		</pre>
		+
		+	== Links ==
		+	* [https://events.linuxfoundation.org/events/collaboration-summit/stone SystemTap Sans Kernel: A Pure Userspace Backend] [https://events.linuxfoundation.org/images/stories/pdf/lfcs2012_jstone.pdf Slides][http://video.linux.com/videos/systemtap-sans-kernel-a-pure-userspace-backend Video]

	[[Category:Development Tools]]		[[Category:Development Tools]]

← Older revision		Revision as of 10:04, 27 October 2011
Line 140:		Line 140:

	</pre>		</pre>
		+
		+	[[Category:Development Tools]]

@@ Line 45: / Line 45: @@
 parts of the tracing problem, between some of the major tracing projects.
 See the [[Tracing Collaboration Project]] page for more information.
 == Some Performance measurements ==

@@ Line 14: / Line 14: @@
 a trace set (a "tapset"), and run it on a running Linux system, with
 no modification or re-compilation of the system required.  To do this, it
-uses the kernel [[KProbes]] interface and loadable kernel modules to dynamically
+uses the kernel [http://www-users.cs.umn.edu/~boutcher/kprobes/ KProbes] interface and loadable kernel modules to dynamically
 add probe points and newly generated code to the running kernel.

@@ Line 1: / Line 1: @@
-Table Of Contents:
+This page has information about [[System Tap]], which is of interest to embedded developers,
+because tracers are a useful tool for diagnosing problems during product development.
-−
-This page has information about [[System Tap]], which is of interest to CE Linux Forum members,
-because tracers are a useful tool for CE product developers.
 == Introduction ==