On 02.03.10 12:41:18, Peter Zijlstra wrote: > On Tue, 2010-03-02 at 11:53 +0100, Robert Richter wrote: > > > > Only adding the random value will lead to longer sample periods on > > average. To compensate this you could calculate something like: > > > > event->hw.sample_period = event->attr.sample_period + (new_seed & > > mask) - (mask >> 1); > > Or cheat and do something like: > > sample_period ^= (new_seed & mask);
This wont work, it will be asymmetric, e.g. for (event->attr.sample_period & mask) == 0 the offset would be always positive. Only for (event->attr.sample_period & mask) == (mask & ~(mask >> 1)) it is correct. -Robert -- Advanced Micro Devices, Inc. Operating System Research Center email: robert.rich...@amd.com ------------------------------------------------------------------------------ Download Intel® Parallel Studio Eval Try the new software tools for yourself. Speed compiling, find bugs proactively, and fine-tune applications for parallel performance. See why Intel Parallel Studio got high marks during beta. http://p.sf.net/sfu/intel-sw-dev _______________________________________________ perfmon2-devel mailing list perfmon2-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/perfmon2-devel
