OSNews: http://www.osnews.com/story/19182/Intel_Releases_LatencyTop_0_1 Exploring the Future of Computing en-us Copyright 2001-2009, David Adams adam+nospam@osnews.com Tue, 24 Nov 2009 13:36:32 GMT http://www.osnews.com/images/osnews.gif OSNews.com http://www.osnews.com Intel is great on the profiling tools http://osnews.com/thread?296799 http://osnews.com/thread?296799 It is interesting that Intel has done so much work on creating profiling and performance tools for the end user. First powertop and now latencytop, tackling problems and things that otherwise would be a slower, much more tedious process to analyze.

While not as glitzy (or as large) as many projects these tools are a great asset to linux. It will be interesting to see if Intel continues to come up with *top style tools for different problem areas in performance that otherwise might be ignored. Fri, 18 Jan 2008 21:01:00 GMT donotreply@osnews.com (Kokopelli) Comments RE: Intel is great on the profiling tools http://osnews.com/thread?296800 http://osnews.com/thread?296800 Agreed. People often don't realize that the first step to fixing any performance problem is being able to measure the problem accurately, so you don't waste time fixing the wrong thing. Often the bottleneck is where a developer would never expect it to be. Fri, 18 Jan 2008 21:19:00 GMT donotreply@osnews.com (JoeBuck) Comments Technology from the 90's http://osnews.com/thread?296801 http://osnews.com/thread?296801 Encouraging customers to look at latencies for performance analysis is really important.

I quickly browsed the code, and it appears that this is implemented by statically defining latency metrics in the kernel. Wow! Was this written a decade ago?

Performance analysis these days is about dynamic tracing using DTrace, which appears in Solaris 10, MacOS X, and other operating systems. DTrace is able to read these latencies and *thousands* more, in *all* layers of the software stack *without* modifying them.

The latencytop engineers need to look at DTrace and not reinvent a wheel that is already obsolete. DTrace does use statically defined trace points at times, but when appropriate and complementary to the dynamic tracing system.

If this tool does get customers to think more carefully about latency metrics, then that will certainly be valuable. All roads lead to DTrace. Fri, 18 Jan 2008 21:20:00 GMT donotreply@osnews.com (bgregg) Comments RE: Technology from the 90's http://osnews.com/thread?296873 http://osnews.com/thread?296873 Linux 2.6.24 has a static probing subsystem, why the latencytop patches don't use it is beyond me Sat, 19 Jan 2008 12:49:00 GMT donotreply@osnews.com (diegocg) Comments SystemTap http://osnews.com/thread?296936 http://osnews.com/thread?296936 What about SystemTap? Isn't it sponsored by Intel? I wonder if all these different utilites couldn't just be integrated with SystemTap, instead of being their own thing. I'll still have to give it a try, PowerTop is a very cool utility that has no doubt saved me plenty of battery life. Sun, 20 Jan 2008 03:43:00 GMT donotreply@osnews.com (abraxas) Comments RE: Technology from the 90's http://osnews.com/thread?297009 http://osnews.com/thread?297009 Dtrace's license is not compatible with the license of the linux kernel. So we have to wait until either Linus decides to go for GPL v3 or Sun allows DTrace to be used in the linux kernel... Mon, 21 Jan 2008 00:21:00 GMT donotreply@osnews.com (superstoned) Comments RE[2]: Technology from the 90's http://osnews.com/thread?297042 http://osnews.com/thread?297042
Dtrace's license is not compatible with the license of the linux kernel. So we have to wait until either Linus decides to go for GPL v3 or Sun allows DTrace to be used in the linux kernel...


You might want to read through the comments here:

http://blogs.sun.com/ahl/entry/dtrace_knockoffs

which was also discussed on osnews here:

http://osnews.com/comments/18388

Based on everything I know about the issue, the actual stopper for DTrace on Linux is Not Invented Here Syndrome. License discussion led to debate about what is or isn't considered a derived work of the kernel, and ways Linux can work around that to include DTrace. Mon, 21 Jan 2008 18:43:00 GMT donotreply@osnews.com (bgregg) Comments