[Tim tells Mark that his observations reflect more Brownian motion (pseudo!) than reality...] > [Mark Favas] > > it being a Tru64 Unix alpha processor machine, I do see a slowdown > > after applying the patch (measured on the test suite and on pystone). > > However, it's only of the order of 0.5 to 1%. > > Now that's very odd, since Alpha has about the slowest integer divsion on > Earth, and every list append was doing an int div before the patch but not > after. > > I'm afraid that timing the test suite before and after is a red herring, as > several of the expensive tests have (pseudo)random components and can do an > amount of work that varies depending on system time at the time random.py is > first imported. > > pystone is even odder: the relevant code in listobject.c is never executed > during pystone! I suspected that because pystone is an old synthetic Ada > benchmark simulating a pile of integer systems programs, so pystone is > unique among Python programs in not exercising any of Python's useful > features <wink> -- a breakpoint in the debugger just now confirmed it (never > did a list resize after compilation finished). > > So I'm pretty sure that after I check it in, you'll see a speedup instead > <wink>. OK <grin>: this time, instead of making unwarranted assumptions about test suites and pystones <wink>, I wrote and ran a test that I _think_ should exercise the code (at least, it does lots of list.append()s), and, yes, the newly checked-in code's about 3-4% faster compared with the original version of, well, days ago. > > Get anywhere identifying why your other app is 20% slower (blast from the > past)? No, not yet. The profiling results at first eyeball seemed hard to match up, so I put it off for a rainy weekend. And Perth's drought has just broken... Will attempt to make sense of it. Interesting that Marc Andre seemed to get a somewhat similar slowdown between 1.52 and 2.0. -- Mark Favas - m.favas@per.dem.csiro.au CSIRO, Private Bag No 5, Wembley, Western Australia 6913, AUSTRALIA
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