Tiered compilation

[abies]

"Use C1 as fast compiler in a tiered system with C2"
http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=6272349

Do I see the light at the end of the tunnel ?

Do you know if it will be enabled for all the platforms before final release of 1.6 ?

[swpalmer]

Release fixed says "Dolphin (b81)"

Dolphin is Java 7.
but b81 seems to refer to the Mustang build.

The evaluation only mentions solaris.  It looks like this is just preparing for tiered compilation in the Dolphin release.

[fatcatair]

Yes there is light at the end of the tunnel and it isn't the train. The final runtime pieces of tiered compilation got putback into mustang. We don't build the tiered system though. At the moment it is buildable only on solaris but that is only a makefile issue all the runtime pieces and compiler pieces are present. That isn't to say that it doesn't need lots of tuning. There are lots of policy decisions that are being worked on but those code changes will be trivial compared to what has been done during mustang. Unfortunately I was quite fast enough. The intention with the recent putback is that I (we) expect that there will be pressure to backport it into an update release of mustang so the last major code changes got put into place now.

I have done some benchmarking of the tiered system on x86 and sparc (no amd64 since we need a client compiler). At the moment the numbers are encouraging.  Typically we see startup performance as good as with client but final performance is either a little lower or a little higher than using -server.   I'll be part of a group presentin at Java One on "New Compiler Optimizations in the Java HotSpot™ Virtual Machine" and I hope to have some more performance data there but we'll see. It will certainly cover some of the work in getting tiered ready,

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[princec]

You heard it here first!

Nice that JGO is always at the forefront of real JVM performance issues

Cas

[swpalmer]

Thanks for the clarification fatcatair... this is welcome news... and please stick around now that you're here.  I'm sure this particular forum can really benefit from your presence.

[Linuxhippy]

Thanks a lot, tired compilation is one of the features which I guess can help java on desktop a lot - I am really interested which impact this will have on swing applications :-)
Waiting for it till dolphin would have been really sad, great to here that almost all code is there :-)
:-) :-) :-) :-) :-) :-) :-) :-) :-) :-) :-) :-)

Do you have any ideas how this will impact startup-speed (since C2 is larger than C1 and now both have to be loaded) and memory footprint? Is it in the 10-20% range?

Thanks a lot for this improvement, I've been waiting for it since ... well I guess when I first heard about it

lg Clemens