RFR(trivial): 8213695: gc/TestAllocateHeapAtMultiple.java is slow in some configs

[Kim Barrett]

> On Jan 19, 2019, at 10:17 AM, sangheon.kim at oracle.com wrote:
> 
> Hi Kishor,
> 
> Sending to 'hotspot-gc-dev' as well.
> 
> On 1/17/19 6:42 PM, Kharbas, Kishor wrote:
>> Greetings,
>>  
>> I ran this test multiple times on Linux & Windows and the tests complete in less than a second. However, I do not have a sparc system to test (if I am correct, earlier discussion pointed that timeout issue is seen on sparc).
>>  
>> My guess of what is happening is – For testing purposes we use the file system of the test directory, instead of a dax filesystem for nv-dimm. With the AllocateHeapAt flag set, heap memory is mapped to a temporary file in the test directory. Depending on the test environment (filesystem, memory, disk, etc), heap memory access might be quite slower.
>>  
>> So I think we should decrease the heap size of the tests. The 5th & 6th subtests can be changed to use 32M instead of 4G. The 4th subtest can be removed.
>>  
>> Here is the patch with the changes - http://cr.openjdk.java.net/~kkharbas/8213695/webrev.00/
> Looks good to me.
> And I can sponsor this patch, but we need a review from a (R)eviewer.
> 
> FYI, I tested the patch on sparc machines(same kind of machines which reported the problem) for 40 times and its run time was mostly less than 3 seconds.

Looks good.