Luca's meaningless thoughts  

What every programmer should know about memory

by Leandro Lucarella on 2010- 06- 01 23:53 (updated on 2010- 06- 01 23:53)
tagged book, cache, en, memory, programming, ulrich drepper, vm - with 0 comment(s)

This LWN large article looks like a very interesting read (specially for people like me that have a very vague idea about modern memory systems):

Ulrich Drepper recently approached us asking if we would be interested in publishing a lengthy document he had written on how memory and software interact. We did not have to look at the text for long to realize that it would be of interest to many LWN readers. Memory usage is often the determining factor in how software performs, but good information on how to avoid memory bottlenecks is hard to find. This series of articles should change that situation.

The original document prints out at over 100 pages. We will be splitting it into about seven segments, each run 1-2 weeks after its predecessor. Once the entire series is out, Ulrich will be releasing the full text.

The full paper in PDF format is also available.

KLEE, automatically generating tests that achieve high coverage

by Leandro Lucarella on 2009- 10- 20 14:20 (updated on 2009- 10- 20 14:20)
tagged coverage, d, en, klee, llvm, software, test, vm - with 2 comment(s)

This is the abstract of the paper describing KLEE, a new LLVM sub-project announced with the upcoming 2.6 release:

We present a new symbolic execution tool, KLEE, capable of automatically generating tests that achieve high coverage on a diverse set of complex and environmentally-intensive programs. We used KLEE to thoroughly check all 89 stand-alone programs in the GNU COREUTILS utility suite, which form the core user-level environment installed on millions of Unix systems, and arguably are the single most heavily tested set of open-source programs in existence. KLEE-generated tests achieve high line coverage — on average over 90% per tool (median: over 94%) — and significantly beat the coverage of the developers' own hand-written test suites. When we did the same for 75 equivalent tools in the BUSYBOX embedded system suite, results were even better, including 100% coverage on 31 of them. We also used KLEE as a bug finding tool, applying it to 452 applications (over 430K total lines of code), where it found 56 serious bugs, including three in COREUTILS that had been missed for over 15 years. Finally, we used KLEE to cross-check purportedly identical BUSYBOX and COREUTILS utilities, finding functional correctness errors and a myriad of inconsistencies.

I have to try this...