Keith Bierman's Weblog

Tuesday December 06, 2005

What I want to work with next. Typically one blogs about what one has done, or has discovered. In this entry, I'll talk about an area I want to spend some time working in RealSoonNow.

As a performance analyst, much of my work has been reductionist. That is, I take some application and make it go faster. Step 0 is to measure it before doing anything to it, followed by figuring out little bits that don't go as fast as they ought (or determining that the wrong algorithms were used, and doing some wholesale surgery ;>) and iterating. The key has always been to isolate the smallest bits possible (faster turnaround, better leverage, etc.). And such work has been rewarding in many different ways. But most of the time, my computers are not focused on running just one application.

My laptop, for example, currently has over 300 threads in 80 processes running. I'm not even driving it very hard. If I want to focus on any of the specific processes or threads, tools such as Performance Analyzer (or it's earlier, more primitive predecessors, such as gprof) are fine.

But if what I really want to do is to maximize the performance of the overall system (throughput) I've largely been toolless.

Worse, everything that my friends at Intel (see their last couple of Intel Developer Fora) have been saying is that they are going to move to a strongly multicore strategy (Justin Rattner spoke of hundreds to thousands of cores, and ElReg reported this as http://www.theregister.co.uk/2005/03/04/intel_100_core/). 

With the DProfile utility (keyword dataspace if you want to search for it at docs.sun.com) developed by Nicolai Kosche and friends, it's now possible to see how all the various threads and processes actually interact inside the memory hierarchy.

Of course, this took a lot of infrastructure, SPARC needed to supply enough runtime instrumentations, Solaris the APIs (including Dtrace), the compilers instrumentation (for optimal results), and extensions to the Performance Analyzer to collect and display the appropriate information (this is where that keyword dataspace comes in handy for docs.sun.com searches).

No doubt Intel and Microsoft will eventually have as many threads in a chip as Sun does today with Niagara (2010++??) No doubt, someday Windows+++ will have mature support for highly threaded applications (in addition to robustly supporting heavily loaded systems). Intel has, of course, purchased several suppliers of threaded tools so ... and to be fair, the hardware threads only have to be on a single board to provide much of the same software opportunity (of course, the RAS is much better with just one chip ;>)

But why wait? Clearly such "complicated" environments are no longer the sole province of supercomputer users and major IT departments (and a power desktop user probably has a lot more challenging apps than I have on my laptop, visual processing is easily parallelized....) so getting started now with the next generation of tools is going to be a lot like it must have been for the first radiologists. Lots to learn, with brand new shiny technology!

So keep your eyes peeled for anything from *.sun.com with words like DProfile or dataspace and dig in!

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