RFC (M) 8058968: Compiler time traces should be improved

Vladimir Ivanov vladimir.x.ivanov at oracle.com
Tue Sep 23 16:57:56 UTC 2014


Looks good to me. Thanks for taking care of this long-standing cleanup.

As a request for further improvements, I'd like to see the following:

* More fine grained details about "Incremental Inline"
   We do additional optimization passes during incremental inlining, so 
it'd be great to see where we actually spend time.

* The following information segregated by compiler type (C1/C2):
   Total compiled methods   :  19359 methods
     Standard compilation   :  19298 methods
     On stack replacement   :     61 methods
   Total compiled bytecodes : 4777417 bytes
     Standard compilation   : 4717650 bytes
     On stack replacement   :  59767 bytes
   Average compilation speed:  20330 bytes/s

   nmethod code size        : 107922240 bytes
   nmethod total size       : 201508520 bytes

* Additional statistics about Tiered compilation (compilation task 
counts per level) would be useful here as well.

I'm fine if these enhancements go is as separate changes though.

Best regards,
Vladimir Ivanov

On 9/23/14, 7:56 PM, Aleksey Shipilev wrote:
> Hi,
> Current C1/C2 compiler time tracing is old and rusty: we have separate
> VM options for C1 and C2 compilers; C2 tracking ignores CompilerBroker
> (mostly), and doing the tracking on its own; bailouts and invalidates
> are ignored in time tracks; and significant parts of compiler code are
> not timed accurately.
> We need to fix that for any future compiler performance work to succeed.
> Our next stop in Nashorn/warmup performance endeavor would probably be
> the native compilers performance.
> I submitted this RFE to track:
>    https://bugs.openjdk.java.net/browse/JDK-8058968
> Current patch is here, and comments are welcome:
>    http://cr.openjdk.java.net/~shade/8058968/webrev.01/
> This code was only compiled on my dev Linux x86_64, and haven't yet been
> in JPRT.
> Summary of changes:
>   * Removes -XX:-TimeCompiler and -XX:-TimeCompiler2, and uses
> -XX:+CITime and -XX:+CITimeVerbose consistently.
>   * CompilerBroker is now responsible for printing the stats for both C1
> and C2.
>   * CompilerBroker now counts the time spent in bailed out compilations
> as well. We are spending significant time there in Nashorn (bug to
> follow), and omitting these compilation from total times ruin the
> summaries (i.e. "C1+C2 > Total" looks really weird.
>   * C2 probes are turned into a product probes: there is little reason to
> have them in fastdebug only, because our performance workloads are
> executed with product bits, and we need statistics there. C1 already
> does it in product mode.
>   * C2 probes are collapsed into a array, and enumerated event names are
> used, like in C1.
>   * Additional C1 and C2 probes are added to cover "blind spots".
> Compare the output:
>   http://cr.openjdk.java.net/~shade/8058968/old-output.txt
>   http://cr.openjdk.java.net/~shade/8058968/new-output.txt
> Thanks,
> -Aleksey.

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