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From "Egor Pasko (JIRA)" <j...@apache.org>
Subject [jira] Updated: (HARMONY-5396) [drlvm][em] excess ValueProfiler locking causes degradation on JITted code with profiling
Date Thu, 07 Feb 2008 19:49:08 GMT

     [ https://issues.apache.org/jira/browse/HARMONY-5396?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Egor Pasko updated HARMONY-5396:
--------------------------------

    Attachment: 0002-value-profiling-options-locked-flagged_all-flagged_insert-unsafe.txt

attaching implementation of value profiling options: locked, flagged_all, flagged_insert,
unsafe (see comments in code for description of those)

patch: 0002-value-profiling-options-locked-flagged_all-flagged_insert-unsafe.txt

how the modified GenericQuicksort test runs:
1. since table inserts are rare and the test is single-threaded FLAGGED_INSERT is essentially
the same as LOCKED and UNSAFE
2. LOCKED improved 2x in speed if compared to the original locking strategy
3. FLAGGED_ALL is 15% slower than FLAGGED_INSERT on my laptop (hmm, inserts are not so rare?
needs investigation)
4. if value profile instrumentation is OFF, first iteration runs 3x faster, definitely want
to patch the code with nops when profile is ready, such a waste of resources!

it would be interesting to see which strategy is best on a multi-threaded application on an
SMP



> [drlvm][em] excess ValueProfiler locking causes degradation on JITted code with profiling
> -----------------------------------------------------------------------------------------
>
>                 Key: HARMONY-5396
>                 URL: https://issues.apache.org/jira/browse/HARMONY-5396
>             Project: Harmony
>          Issue Type: Improvement
>          Components: DRLVM
>            Reporter: Aleksey Shipilev
>            Assignee: Egor Pasko
>         Attachments: 0001-ValueProfileCollector-refactoring-to-separate-FirstN-and-Divided-methods.txt,
0002-value-profiling-options-locked-flagged_all-flagged_insert-unsafe.txt, 0002-ValueProfileCollector-implementing-locking-strategies.txt,
HARMONY-5396-syncTie.patch
>
>
> During investigation of serious slowdown in some microbenchmark, excess locking in ValueProfiler
was identified. 
> Please see Harmony-dev thread for the details: http://markmail.org/message/tatsfbyb7eb3q3rr

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