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Oracle To Bring Dtrace To Linux
mvar writes "Dtrace co-author Adam Leventhal writes on his blog about Dtrace for Linux: 'Yesterday (October 4, 2011) Oracle made the surprising announcement that they would be porting some key Solaris features, DTrace and Zones, to Oracle Enterprise Linux. As one of the original authors, the news about DTrace was particularly interesting to me, so I started digging. Even among Oracle employees, there's uncertainty about what was announced. Ed Screven gave us just a couple of bullet points in his keynote; Sergio Leunissen, the product manager for OEL, didn't have further details in his OpenWorld talk beyond it being a beta of limited functionality; and the entire Solaris team seemed completely taken by surprise. Leunissen stated that only the kernel components of DTrace are part of the port. It's unclear whether that means just fbt or includes sdt and the related providers. It sounds certain, though, that it won't pass the DTrace test suite which is the deciding criterion between a DTrace port and some sort of work in progress.'"
If you want Dtrace and ZFS, just go with FreeBSD. You get pf and jails thrown in for the effort.
This is a great technology story - even if only for one version of Linux so far. DTrace will bring tremendous value for troubleshooting and performance analysis, and is a technology I use (almost) every day.
For example, yesterday I had a CPU bound workload with an unexpected level of variation, and used DTrace to measure the effect of CPU thread affinity and interrupt activity on that workload. I used DTrace to pull the runtime along with other details: number of scheduling events for that thread, along with the CPUs that the thread ran on; also, for preemption, the pre-emptor thread (to see why) along with both its user-level and kernel stack traces; also the interrupt thread and device. I fairly quickly showed that the runtime variation was caused by network interface interrupts from an entirely different application. This analysis would take quite a lot longer without DTrace, and may be prohibitively difficult to complete.
Many of my uses of DTrace are much more straightforward than that; including identifying file system latency for applications, application response time, and CPU dispatcher queue latency. I've listed many more examples in the DTrace book (http://www.dtracebook.com). It should be a great resource of ideas for those looking to use DTrace on Linux - since the hardest part for people has been knowing where to start, given the ability to see everything.