RFR(S): 8142341: GC: current flags need ranges to be implemented

[sangheon.kim]

Hi Dmitry,

Thank you for the review!
Sure I will update my patch related to your enhancement.

Thanks,
Sangheon


On 11/24/2015 06:30 AM, Dmitry Dmitriev wrote:
> Hi Sangheon,
>
> Looks good to me! Thank you for fixing that. I hope that enhancement 
> will be pushed today(currently in JPRT queue), so please update your 
> patch after that!
>
> Thanks,
> Dmitry
>
> On 21.11.2015 0:04, sangheon.kim wrote:
>> Hi all,
>>
>> Could I have a couple of reviews for this change to add explicit 
>> 'range' for flags?
>>
>> Previously, we added 'range' when it is needed to avoid assert/crash 
>> but now explicit 'range' are needed for all flags.
>> All flags should have 'range' or 'constraint' at least.
>>
>> CR: https://bugs.openjdk.java.net/browse/JDK-8142341
>> Webrev: http://cr.openjdk.java.net/~sangheki/8142341/webrev.00
>> Testing: JPRT, RBT 
>> (hotspot/test/:hotspot_all,testlist,noncolo.testlist 
>> --add-tonga-keyword quick), hotspot/test/runtime/CommandLine for 
>> embedded
>>
>> * Summary
>> 1. Added 3 new constraint functions.
>>    1) HeapBaseMinAddress: Added to avoid an overflow after align up 
>> and this flag makes hang up without constraint function. (newly added 
>> as a part of GC work)
>>    2) TLABWasteIncrement: Without this constraint function we don't 
>> have problems (even many GCs happen). But added to avoid an overflow 
>> at ThreadLocalAllocBuffer::record_slow_allocation(). There are also 
>> separate CR for this overflow ( JDK-8143352 ).
>>    3) NUMAInterleaveGranularity: Added to avoid an overflow after 
>> align up.
>>
>> 2. Some flags have narrower range than their type.
>>    1) Here's the reason why some flags should have different range. 
>> (same order from globals.hpp)
>> {flag type} {flag name}: (range), {comment}
>> size_t NUMAInterleaveGranularity: (os::vm_allocation_granularity(), 
>> max_uintx), there is a comment at numa_interleaving_init() that this 
>> flag should be larger than vm_allocation_granularity().
>> uintx CMSOldPLABReactivityFactor: (1,max_uintx), couldn't be zero as 
>> used for multiplication
>> uintx CMS_FLSPadding: (0, max_juint), used to set a function which 
>> has 'unsigned int' type input parameter.
>> uintx CMS_SweepPadding: (0, max_juint), used to set a function which 
>> has 'unsigned int' type input parameter.
>> intx CMSWaitDuration: (min_jint, max_jint), used to set a function 
>> which has 'long' type input parameter.
>> uintx PausePadding: (0, max_juint), used to set a function which has 
>> 'unsigned int' type input parameter.
>> uintx PromotedPadding: (0, max_juint), used to set a function which 
>> has 'unsigned int' type input parameter.
>> uintx SurvivorPadding: (0, max_juint), used to set a function which 
>> has 'unsigned int' type input parameter.
>> uintx AdaptiveSizePolicyCollectionCostMargin: (0, 100), as this flag 
>> is divided by 100 I assume this is percentage.
>> uintx GCTimeRatio: (0, max_juint), used to set a function which has 
>> 'unsigned int' type input parameter.
>> intx PrefetchCopyIntervalInBytes: (-1, max_jint)
>> intx PrefetchScanIntervalInBytes:  (-1, max_jint)
>> intx PrefetchFieldsAhead:  (-1, max_jint), I think these 3 Prefetch* 
>> flags should have same upper limit and looking at their related codes 
>> 'max_jint' seems appropriate ( no problem with 'max_jint' during 
>> testing). However, as Prefetch::read/write() needs 'intx', 'intx' 
>> also seems good but we have to fix some codes (maybe including 
>> generated codes).
>> uintx CPUForCMSThread: (0, max_juint), used to set a function which 
>> has 'unsigned int' type input parameter.
>> uintx ProcessDistributionStride: (0, max_juint), used to set uint 
>> variable and used 'for loop' which has uint increment. i.e. for (uint 
>> i=0; i<ProcessDistributionStride; i++)
>> uintx CMSCoordinatorYieldSleepCount: (0, max_juint), used at 
>> 'increment for loop()' as max value and the increment is uint.
>> uintx CMSYieldSleepCount: (0, max_juint),  used at 'increment for 
>> loop()' as max value and the increment is uint.
>> uintx TLABRefillWasteFraction: (1, max_juint), used as a return value 
>> of uint type function and for division. i.e. uint 
>> GCTLABConfiguration::tlab_refill_waste_limit()() { return 
>> TLABRefillWasteFraction; }
>> uintx TLABWasteIncrement: (0, max_jint), type cast to (int)
>> intx PrintCMSStatistics: (0,2), flag to choose print mode and we only 
>> use " if (a !=0, >0, >1)".
>> intx PrintFLSStatistics: (0,2), flag to choose print mode and we only 
>> use " if (a !=0, >0, >1)".
>> intx PrintFLSCensus: (0,1), flag to choose print mode and we only use 
>> " if (a !=0, >0)".
>> uintx GCDrainStackTargetSize: (0, max_juint), type cast to 'unsigned 
>> int'
>>
>> (g1_globals.hpp)
>> intx G1ConcRefinementThresholdStep: (0, max_jint), used to set (int) 
>> type variable.
>>
>> 3. Excluded flags from TestOptionsWithRanges.java
>> 1) Memory and thread related flags: tests for these flags will 
>> consume too many resources from the system.
>> 2) VMThreadStackSize: range work for this flag is not included in 
>> this patch but I faced OOME several times, so excluded.
>>
>> * I will reflect Dmitry's enhancement(JDK-8143038: [TESTBUG] 
>> TestOptionsWithRanges: allow excluding only a subset of tested values 
>> specified for a flag) next time.
>>
>> Thanks,
>> Sangheon
>>
>>
>>
>