Xiao Feng, Thanks for a good question. The optimization improves so-called "peak score" which is calculated from several subsequent executions. If you cache VM state in different files for different command lines, you may even cache pre-compiled class files for a particular benchmark. As I've got from a fellow SPEC committee member this optimization is allowed unless the released VM is specifically tuned to pass the spec.
Sorry about the third bullet. Well, I thought if I should mention pre-compiled classes there. I hesitate because I don't know any trusted research which shows that loading pre-compiled classes from disk is quicker than dynamic re-compilation. Thanks! On Thu, Oct 23, 2008 at 10:21 AM, Xiao-Feng Li <[EMAIL PROTECTED]> wrote: > On Thu, Oct 23, 2008 at 1:44 PM, Alexei Fedotov > <[EMAIL PROTECTED]> wrote: >> Hello Wenlong, >> You have addressed a very interesting topic. Let me share few ideas >> how to approach it: >> >> 1. The first thing I would expect to understand here is why we should >> care about "Hello, World" startup. SPEC jvm [0] startup scores are >> much more tempting to approach. Then one should compare the score with >> one of our competitors. Taking into account that 300 ms = 300 context >> switches I would not say that the number itself makes me unhappy about >> Harmony speed. >> >> 2. Due to some bureaucracy the following tempting [1] idea is still >> waiting for an experienced and accurate C coder to complete: >> * load classes into bootstrap class loader once >> * store the internal representation of classes as a memory mapped file; >> * next time, load the file if it exists. > > Fedotov, thanks. I guess this idea can only improve the second-time > startup time? Is this be useful for SPECJVM startup score? Thanks. > > Btw, your email lost bullet 3. :) > > Thanks, > xiaofeng > >> 4. If you don't like C, there are tunable things in a class library >> you may find using Gregory's JVMTI profiler [2]. >> >> [0] http://www.spec.org/jvm2008/ >> [1] a research shows +10% on "Hello, World" >> [2] two first attachments at >> https://issues.apache.org/jira/browse/HARMONY-4569 >> >> On Thu, Oct 23, 2008 at 12:29 AM, Tim Ellison <[EMAIL PROTECTED]> wrote: >>> >>> Wenlong Li (JIRA) wrote: >>> > The startup time is long for the simple helloworld program. On a Core >>> > 2 Quad-core processor, running the simple helloworld program will take >>> > more than 300 ms. >>> > Can we reduce the startup cost? >>> >>> Yes, I hope so ... concrete suggestions or analysis of startup costs are >>> welcome. >>> >>> Regards, >>> Tim >> >> >> >> -- >> With best regards, >> Alexei >> > > > > -- > http://xiao-feng.blogspot.com > -- With best regards, Alexei
