* Jim Meyering wrote on Fri, Jun 13, 2008 at 10:17:36AM CEST: > Ralf Wildenhues <[EMAIL PROTECTED]> wrote: > > > Just ordering the build of some huge objects in GCC allowed to shave 30% > > build time off a parallel build: > > Yes, I did the same with coreutils/tests, and it made a big difference, > since there were some long-running tests near the end of the initial list. > Here it was the first thing I tried, once parallelized. However, in > this case it gave less than 1 second decrease. No big surprise, though, > since even removing the top 4-5 longest-running tests shaves only ~8 > seconds off the total (~11s) run time, now that they're run in parallel.
IIRC most of the coreutils tests are pretty I/O bound. Running them in parallel won't help much, with all of them competing for the same kernel resp. disk resources. I guess the proposed parallel Autotest patches are thus limited, too. I found testing them on tmpfs (/dev/shm) to show much more favorable speedup than disk or NFS. You probably may want to ensure to have a recent kernel, too (although I have no idea whether there were significant improvements in in-kernel parallelism recently). Cheers, Ralf
