Martin Devera schrieb: > I measured it. Lock op in futex based linux locking is of the same > speed as windows critical section and it is about 30 cycles on my > P4 1.8GHz in uncontented case. > As explained in already mentioned http://www.linuxjournal.com/article/6993 > it seems due to pipeline flush during cmpxchg insn. > And there will be cacheline transfer penalty which is much larger. So > that mutex locking will take time comparable with protected code itself > (assuming fast code like dict/list read). > Single compare will take ten times less. > Am I missing something ?
I'll have to wait for your revised algorithm, but likely, you will need some kind of memory barrier also, or else it can't work in the multi-processor case. In any case, if to judge whether 30 cycles is few or little, measurements of the alternative approach are necessary. Regards, Martin _______________________________________________ Python-Dev mailing list Python-Dev@python.org http://mail.python.org/mailman/listinfo/python-dev Unsubscribe: http://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
