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From: Nicholas N. <nj...@cs...> - 2006-03-28 22:23:58
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On Tue, 28 Mar 2006, Julian Seward wrote: >> r5774. memcheck is now in the same ballpark as --tool=none which it >> never has been before. > > Ashley - you mean when you do MPI bandwidth tests? 'cos although > memcheck is much improved as a result of this, it's still nowhere > near as fast as 'none' for computation. For a MPI test though, > in which mostly you're waiting for the nic, all that V is really > doing is painting memory as it goes in/out, as per your ioctls > wrappers, and for this particular case - changing memory permissions - > Nick's work does indeed give a big speedup. Oh yeah, the new version is much faster at changing memory permissions over large areas. perf/sarp.c is a synthetic benchmark that tests this, it runs more than twice as fast now compared to 3.1.1. The real program it was based on runs about 1.6 times faster with the new version. Nick |