Good findings!! Thanks. -xiaofeng 2008/7/4 Aleksey Shipilev <[EMAIL PROTECTED]>: > Hi Gregory, all, > > The performance is important for JRE too. > > BTW, I had profiled spectralnorm benchmark and see following problems: > > 1. Bad instruction selection for integer divide: > > int a; > int b = a / 2; > > generates into: > > mov eax, a > mov ebx, 2 > idiv eax, ebx > > but it's better to > > mov eax, a > shl eax, 1 > > Manual change in Java code brings +60% to spectralnorm performance > (execution time downs from 10secs to 6secs). There should be better > instruction selection for divide operation. Would someone take it? If > not, I would try to produce the patch for Jitrino this weekend. > > > 2. Recompilation events propagation > > Consider the following call chain: > main() --[n times]--> A() --[m times]--> B() > > Now consider, m >> n, then B() should be inlined. But such the > inlining will be done during the recompilation of method A(), which > waits for n to rise up (that's true for current server.emconf with > edge profiler enabled). On first glance, one of the solutions will be > propagation of such recompilation requests up the call chain. Any > ideas here are welcome. > > Thanks, > Aleksey. > > On Fri, Jul 4, 2008 at 1:04 AM, Gregory Shimansky <[EMAIL PROTECTED]> wrote: >> On 4 июля 2008 Aleksey Shipilev wrote: >>> TWIMC, >>> >>> Stefan Krause publishes another review on Java vs. C performance here: >>> http://www.stefankrause.net/wp/?p=9#comments >>> >>> It seems like Harmony has "a long way to go" in performance :) >>> I'm gonna look on some of these tests in near term. >> >> It is interesting to see that IBM is often quite close to Harmony in >> performance. In fact Harmony acts quite well in its current state. I think >> though that performance for Java is always a 2nd priority after stability. >> Look at IBM, its Java is targeted at servers where stability is what is >> important. >> >> Looking at the occasional test failures on the alerts mail list it seems like >> stability is the number one focus for improvement and it is a by far harder >> to move in that direction. >> >> -- >> Gregory >> >
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