RFR 8078555(M): GC: implement ranges (optionally constraints) for those flags that have them missing

[sangheon.kim]

Hi Jon,


On 08/26/2015 03:18 PM, sangheon.kim wrote:
> Hi Jon,
>
> Thank you for the review.
>
> On 08/26/2015 01:57 PM, Jon Masamitsu wrote:
>> http://cr.openjdk.java.net/~sangheki/8078555/webrev.03/src/share/vm/runtime/commandLineFlagConstraintsGC.cpp.frames.html 
>>
>>
>> Seems to me that a user should be able to set the default value for
>> a flag on the command line without getting an error.  Below if I set
>> G1RSetRegionEntries to 0, I get a constraint violation.
> I agree with you.
> Let me change both constraint functions(G1RSetRegionEntries, 
> G1RSetSparseRegionEntries) and related 
> codes(HeapRegionRemSet::setup_remset_size).
Looking at the some flags, our codes are working differently for default 
value of zero vs. manually set value of zero.
We are just calling FLAG_IS_DEFAULT(xxx) to check whether it is 
set(default value) or not.
So it seems like xxx=0 is not recognized as default value even though 
xxx's default value is zero.
What do you think?
Please look at MaxGCPauseMillis, GCPauseIntervalMillis, 
G1RSetSparseRegionEntries and G1RSetRegionEntries.

Thanks,
Sangheon


>
> FYI, if we don't stop with zero by constraint function, it fires 
> assert under current code.
>
> These will be included at next webrev.
>
> Thanks,
> Sangheon
>
>>
>> 271 Flag::Error G1RSetRegionEntriesConstraintFunc(intx value, bool 
>> verbose) {
>> 272 if (!UseG1GC) return Flag::SUCCESS;
>> 273
>> 274 // Default value of G1RSetRegionEntries=0 means will be set 
>> ergonomically.
>> 275 // Minimum value is 1.
>> 276 if (FLAG_IS_CMDLINE(G1RSetRegionEntries) && (value < 1)) {
>> 277 CommandLineError::print(verbose,
>> 278 "G1RSetRegionEntries (" INTX_FORMAT ") must be "
>> 279 "greater than or equal to 1\n",
>> 280 value);
>> 281 return Flag::VIOLATES_CONSTRAINT;
>> 282 } else {
>> 283 return Flag::SUCCESS;
>> 284 }
>> 285 }
>>
>>
>>
>> On 8/26/2015 11:51 AM, sangheon.kim wrote:
>>> Hi Derek,
>>>
>>> Thank you for looking at this!
>>>
>>> On 08/26/2015 10:59 AM, Derek White wrote:
>>>> Hi Sangheon,
>>>>
>>>> I haven't reviewed the actual ranges and constraints yet, but one 
>>>> thing you might want to consider:
>>>>
>>>> For the test cases, you may want synchronize the GC specified to 
>>>> ProcessBuilder with the "@requires gc=" tags. This prevents the 
>>>> test harness from running G1 tests when the test harness is trying 
>>>> to run CMS test, etc, and also avoids potential confusing test 
>>>> failures.
>>>>
>>>>  @requires vm.gc=="G1" | vm.gc=="null"
>>>>  (or specify Parallel GC as needed).
>>> Thank you for the explanation.
>>> I didn't know about this.
>>>
>>> So it seems like vm.gc=="null" means not specifying vm option.
>>>
>>>>
>>>> This is for:
>>>> TestG1ConcMarkStepDurationMillis.java (G1)
>>>> TestObjectTenuringFlags.java (Parallel)
>>>> TestInitialTenuringThreshold.java (Parallel)
>>>> TestG1HeapRegionSize.java (G1)
>>> Okay, I will add these tags at next webrev.
>>>
>>> Thanks,
>>> Sangheon
>>>
>>>
>>>>
>>>>  - Derek
>>>>
>>>> On 8/24/15 5:33 PM, sangheon.kim wrote:
>>>>> Hi Kim,
>>>>>
>>>>> On 08/24/2015 02:16 PM, Kim Barrett wrote:
>>>>>> On Aug 24, 2015, at 3:06 PM, sangheon.kim 
>>>>>> <sangheon.kim at oracle.com> wrote:
>>>>>>> Hi Kim,
>>>>>>>
>>>>>>> Here's webrev.03 which includes your comment for MarkStackSize 
>>>>>>> constraint function.
>>>>>>>
>>>>>>> http://cr.openjdk.java.net/~sangheki/8078555/webrev.03
>>>>>>> http://cr.openjdk.java.net/~sangheki/8078555/webrev.03_to_02/
>>>>>>>
>>>>>>> And all your comments will be managed by 
>>>>>>> https://bugs.openjdk.java.net/browse/JDK-8134348 .
>>>>>> If the value of MarkStackSizeMax were changed later, there's nothing
>>>>>> to verify MarkStackSize is still smaller.  [This is related to my
>>>>>> earlier comment about constraints between options being tested twice
>>>>>> and failures reported twice.]  Do we care in this case?
>>>>> If your concern is something like
>>>>> -XX:MarkStackSize=128 -XX:MarkStackSizeMax=100.
>>>>> Yes, in this case the order is important as ranges and constraint 
>>>>> functions are verified by its order.
>>>>> MarkStackSizeMax will be verified first(its range) and 
>>>>> MarkStackSize will be compared with verified MarkStackSizeMax.
>>>>>
>>>>> And as I said your original concern is current limitation.
>>>>> If we set CMSOldPLABMin and CMSOldPLABMax together with invalid 
>>>>> values (e.g. CMSOldPLABMin=100, CMSOldPLABMax=50),
>>>>> they will print out 2 failure messages.
>>>>>
>>>>> Thanks,
>>>>> Sangheon
>>>>>
>>>>>>
>>>>>> Other than that, looks good.
>>>>>>
>>>>>
>>>>
>>>
>>
>