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From "Egor Pasko (JIRA)" <j...@apache.org>
Subject [jira] Commented: (HARMONY-5396) [drlvm][em] excess ValueProfiler locking causes degradation on JITted code with profiling
Date Tue, 12 Feb 2008 13:19:14 GMT

    [ https://issues.apache.org/jira/browse/HARMONY-5396?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12568101#action_12568101
] 

Egor Pasko commented on HARMONY-5396:
-------------------------------------

Pavel, on your precision concern: Aleksey already checked effect on SPECjbb2005. Quoting:

--
I had measured two modes: (a) locks eliminated completely, (b) addNewValue
is locked only on insertion of new value into the table.

SPECjbb2005: no boost/degradation for overall score, (a) +10% score
improvement for 1st warehouse, (b) +9% score improvement for 1st
warehouse.
--

variant (b) is the current default. I think, this is enough to prove that we can move on with
the current precision

On the question whether we need so many profiling options. I still did not see any benchmarks
sensitive to the choice of locking strategy. But for some reason I believe there are real
cases where locking strategy choice is important. So, I cannot decide what to choose. I left
the options where they are to make some experiments. I am OK to remove redundant ones as soon
as they are proven redundant.

> [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,
0003-value-profiling-options-locked-flagged_all-flagged_insert-unsafe.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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