Tim Prince <n8tm <at> aol.com> writes: > Several possibilities which you haven't addressed may affect this. > Are you comparing the performance of a single thread when locked to a > single core, compared to when it is permitted to rotate among cores, > with or without HyperThread enabled? > I've never run into anyone running win7 32-bit; it may have more such > issues than the more common 64-bit.
The scripts we're using form the basis of a build system to invoke GCC and an assembler lots of times throughout a directory tree of a few thousand items. The tree itself on the file-system is not gigantic. I've tried to make sure that the environment has all the usual suspects disabled (virus-checking disabled, paging completely disabled for all disks, nothing else running in the background) before comparing anything. I've been comparing using 2 different methods, one is the time to clean the tree using "rm -rf" via a makefile on empty directories and the other is to do a full build on a clean tree. When running make we don't use the "-j" option to use multi-threaded builds. When running each testing method, the CPUs are barely loaded at all (10%, maybe) and there's almost no I/O that registers. Hyperthreading is disabled. I've tried comparisons when configuring the PC using msconfig to present 1 core, 2 cores, and 4 cores. The difference between 1-core and 2 or 4 cores is dramatic with 1-core running 2x+ faster. There's almost no difference in speed between 2 cores and 4 cores. The disk is an SSD. I've recently tried launching the original command-line window with its affinity locked to core0 and priority set to "realtime". I've inspected the results using SysInternals' Process Explorer and spawned processes appear to be locked to core0. I made sure that the non-spawned processes like "conhost.exe" also had their affinities set and their priority raised to realtime. There's no difference in processing speed though. Btw, I don't think the issue is I/O. The disk I'm using is an SSD (OCZ Vertex 2) which is fairly fast. But, the results repeat even if I try a regular 7200 RPM hard drive. Yeah, weird. andy -- Problem reports: http://cygwin.com/problems.html FAQ: http://cygwin.com/faq/ Documentation: http://cygwin.com/docs.html Unsubscribe info: http://cygwin.com/ml/#unsubscribe-simple