RFR(S) Contended Locking fast notify bucket (8075171)
Karen Kinnear
karen.kinnear at oracle.com
Thu Jul 9 13:20:48 UTC 2015
Dan,
ship it!
thanks,
Karen
On Jul 9, 2015, at 2:40 AM, David Holmes wrote:
> On 9/07/2015 8:10 AM, Daniel D. Daugherty wrote:
>>
>> On 7/8/15 12:06 PM, Daniel D. Daugherty wrote:
>>> On 7/8/15 11:53 AM, Karen Kinnear wrote:
>>>> Dan,
>>>>
>>>> Looks good.
>>>>
>>>> Only comment is -
>>>>
>>>> In ObjectMonitor::INotify - lines 1668-1671
>>>> the default value of policy is "2"
>>>> -- which basically is "b" not "a" unless the EntryList is empty.
>>>
>>> Nice catch! For folks on the alias that don't have this code
>>> tattooed on the inside of their eyelids. This is the relevant code:
>>>
>>> src/share/vm/runtime/objectMonitor.cpp:
>>>
>>> 136 static int Knob_MoveNotifyee = 2; // notify() -
>>> disposition of notifyee
>>>
>>> <snip>
>>>
>>> 1659 void ObjectMonitor::INotify(Thread * Self) {
>>> 1660 const int policy = Knob_MoveNotifyee;
>>>
>>> <snip>
>>>
>>> 1668 // Disposition - what might we do with iterator ?
>>> 1669 // a. add it directly to the EntryList - either tail or head.
>>> 1670 // b. push it onto the front of the _cxq.
>>> 1671 // For now we use (a).
>>>
>>> <snip>
>>>
>>> 1710 } else if (policy == 2) { // prepend to cxq
>>>
>>> I will update the comment.
>>
>> Don't think this update is worth a new webrev so here
>> are the diffs instead:
>>
>> $ diff src/share/vm/runtime/objectMonitor.cpp{.cr1,}
>> 1669,1671c1669,1672
>> < // a. add it directly to the EntryList - either tail or head.
>> < // b. push it onto the front of the _cxq.
>> < // For now we use (a).
>> ---
>> > // a. add it directly to the EntryList - either tail (policy == 1)
>> > // or head (policy == 0).
>> > // b. push it onto the front of the _cxq (policy == 2).
>> > // For now we use (b).
>>
>> Thanks again for the catch!
>
> Yep good catch!
>
> David
>
>> Dan
>>
>>
>>>
>>> Dan
>>>
>>>
>>>>
>>>> thanks,
>>>> Karen
>>>>
>>>> On Jul 3, 2015, at 8:11 PM, Daniel D. Daugherty wrote:
>>>>
>>>>> Greetings,
>>>>>
>>>>> I've updated the patch for Contended Locking fast notify bucket
>>>>> based on David H's and Karen's comments.
>>>>>
>>>>> This work is being tracked by the following bug ID:
>>>>>
>>>>> JDK-8075171 Contended Locking fast notify bucket
>>>>> https://bugs.openjdk.java.net/browse/JDK-8075171
>>>>>
>>>>> Here is the webrev URL:
>>>>>
>>>>> http://cr.openjdk.java.net/~dcubed/8075171-webrev/1-jdk9-hs-rt/
>>>>>
>>>>> Here is the JEP link:
>>>>>
>>>>> https://bugs.openjdk.java.net/browse/JDK-8046133
>>>>>
>>>>> Testing:
>>>>>
>>>>> - RBT vm.quick batches (in process)
>>>>> - JPRT test jobs
>>>>> - MonitorWaitNotifyStresser micro-benchmark (in process)
>>>>> - CallTimerGrid stress testing (in process)
>>>>>
>>>>>
>>>>> The changes in this round are in only four of the files:
>>>>>
>>>>> src/share/vm/opto/runtime.cpp
>>>>>
>>>>> - deleted comment about hashCode() that belongs in a different bucket
>>>>>
>>>>> src/share/vm/runtime/objectMonitor.cpp
>>>>>
>>>>> - add MAX_RECHECK_INTERVAL define for use in ObjectMonitor::EnterI()
>>>>> - cleanup recheck interval code
>>>>> - ObjectMonitor::INotify() return type is now "void"
>>>>> - delete duplicate comments, clarify/rewrite some comments
>>>>>
>>>>> src/share/vm/runtime/objectMonitor.hpp
>>>>>
>>>>> - ObjectMonitor::INotify() return type is now "void"
>>>>>
>>>>> src/share/vm/runtime/synchronizer.cpp
>>>>>
>>>>> - clarify/rewrite comments, add additional comments
>>>>> - cleanup variables in ObjectSynchronizer::quick_notify
>>>>> - refactor loop to be more clear
>>>>> - delete unused enum MaximumRecheckInterval
>>>>>
>>>>> The easiest way to review the delta is to download the two patch
>>>>> files and compare them in something like jfilemerge:
>>>>>
>>>>> http://cr.openjdk.java.net/~dcubed/8075171-webrev/0-jdk9-hs-rt/hotspot.patch
>>>>>
>>>>> http://cr.openjdk.java.net/~dcubed/8075171-webrev/1-jdk9-hs-rt/hotspot.patch
>>>>>
>>>>>
>>>>> Dan
>>>>>
>>>>>
>>>>> On 5/18/15 2:07 PM, Daniel D. Daugherty wrote:
>>>>>> Greetings,
>>>>>>
>>>>>> I have the Contended Locking fast notify bucket ready for review.
>>>>>>
>>>>>> The code changes in this bucket are the final piece in the triad
>>>>>> of {fast-enter, fast-exit, fast-notify} changes. There are no
>>>>>> macro assembler changes in this bucket (yeah!), but there are
>>>>>> code review cleanups motivated by comments on other buckets, e.g.,
>>>>>> changing variables like 'Tally' -> 'tally'.
>>>>>>
>>>>>> This work is being tracked by the following bug ID:
>>>>>>
>>>>>> JDK-8075171 Contended Locking fast notify bucket
>>>>>> https://bugs.openjdk.java.net/browse/JDK-8075171
>>>>>>
>>>>>> Here is the webrev URL:
>>>>>>
>>>>>> http://cr.openjdk.java.net/~dcubed/8075171-webrev/0-jdk9-hs-rt/
>>>>>>
>>>>>> Here is the JEP link:
>>>>>>
>>>>>> https://bugs.openjdk.java.net/browse/JDK-8046133
>>>>>>
>>>>>> Testing:
>>>>>>
>>>>>> - Aurora Adhoc RT/SVC baseline batch
>>>>>> - JPRT test jobs
>>>>>> - MonitorWaitNotifyStresser micro-benchmark (in process)
>>>>>> - CallTimerGrid stress testing (in process)
>>>>>> - Aurora performance testing:
>>>>>> - out of the box for the "promotion" and 32-bit server configs
>>>>>> - heavy weight monitors for the "promotion" and 32-bit server
>>>>>> configs
>>>>>> (-XX:-UseBiasedLocking -XX:+UseHeavyMonitors)
>>>>>> (in process)
>>>>>>
>>>>>> The hang somehow introduced by the "fast enter" bucket is still
>>>>>> unresolved, but progress is being made. That work is being tracked
>>>>>> by the following bug:
>>>>>>
>>>>>> JDK-8077392 Stream fork/join tasks occasionally fail to complete
>>>>>> https://bugs.openjdk.java.net/browse/JDK-8077392
>>>>>>
>>>>>> You'll see a change that re-enables the "fast enter" bucket in this
>>>>>> webrev, but that change will not be pushed when we're done with the
>>>>>> review of this bucket unless JDK-8077392 is resolved.
>>>>>>
>>>>>> Thanks, in advance, for any comments, questions or suggestions.
>>>>>>
>>>>>> Gory details about the changes are below...
>>>>>>
>>>>>> Dan
>>>>>>
>>>>>>
>>>>>> 8075171 summary of changes:
>>>>>>
>>>>>> src/share/vm/classfile/vmSymbols.hpp
>>>>>> - Add do_intrinsic() entries for _notify and _notifyAll
>>>>>>
>>>>>> src/share/vm/opto/library_call.cpp
>>>>>> - Add optional inline_notify() that is controlled by new
>>>>>> '-XX:[+-]InlineNotify' option
>>>>>>
>>>>>> src/share/vm/opto/runtime.cpp
>>>>>> src/share/vm/opto/runtime.hpp
>>>>>> - Add OptoRuntime::monitor_notify_C() and
>>>>>> OptoRuntime::monitor_notifyAll_C() functions to support
>>>>>> the new "fast notify" code paths
>>>>>> - Add new OptoRuntime::monitor_notify_Type() to support
>>>>>> the above two new functions
>>>>>>
>>>>>> src/share/vm/runtime/globals.hpp
>>>>>> - Add '-XX:[+-]InlineNotify' option; default option value is
>>>>>> enabled (true)
>>>>>>
>>>>>> src/share/vm/runtime/objectMonitor.cpp
>>>>>> src/share/vm/runtime/objectMonitor.hpp
>>>>>> - Refactor ObjectMonitor::notify() and ObjectMonitor::notifyAll()
>>>>>> into wrappers that call the new ObjectMonitor::INotify()
>>>>>> - Add new ObjectMonitor::INotify() to reduce code duplication
>>>>>> between "notify" and "notifyAll" code paths
>>>>>>
>>>>>> src/share/vm/runtime/sharedRuntime.cpp
>>>>>> - Temporarily re-enable the "fast enter" optimization in order
>>>>>> to do performance testing. JDK-8077392 is still unresolved,
>>>>>> but progress is being made.
>>>>>>
>>>>>> src/share/vm/runtime/synchronizer.cpp
>>>>>> src/share/vm/runtime/synchronizer.hpp
>>>>>> - Add ObjectSynchronizer::quick_notify() that implements the
>>>>>> new "fast notify" code paths
>>>>>> - The new code handles a couple of special cases where the
>>>>>> "notify" can be done without the heavy weight slow-path
>>>>>> (thread state transitions and other baggage)
>>>>>>
>>>>>>
>>>
>>>
>>>
>>
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