RFR(s): 8152160: SIGFPE in CompactibleFreeListSpaceLAB::compute_desired_plab_size

[Jon Masamitsu]

On 3/22/2016 10:19 AM, sangheon wrote:
> Hi Per,
>
> Thank you for reviewing this issue.
>
> On 03/22/2016 08:59 AM, Per Liden wrote:
>> Hi Sangheon,
>>
>> On 2016-03-22 03:12, sangheon wrote:
>>> Hi all,
>>>
>>> Could I have a couple of reviews for this change?
>>>
>>> With large value of CMSOldPLABNumRefills, SIGFPE would happen at
>>> CompactibleFreeListSpaceLAB::compute_desired_plab_size() because 
>>> related
>>> routine would be zero by an overflow.
>>>
>>> Type-casting to 'double' before the problematic division will resolve
>>> the problem.
>>
>> Casting to double doesn't quite seem like the right thing to do here. 
>> Can't this be rephrased to avoid the overflow completely, something 
>> like:
>>
>> _global_num_blocks[i] / _global_num_workers[i] / CMSOldPLABNumRefills
> You are right!
> I like this much more.
>
> Webrev: http://cr.openjdk.java.net/~sangheki/8152160/webrev.01

Looks good.

Jon

>
> Sangheon
>
>>
>> cheers,
>> Per
>>
>>>
>>> CR: https://bugs.openjdk.java.net/browse/JDK-8152160
>>> Webrev: http://cr.openjdk.java.net/~sangheki/8152160/webrev.00
>>> Testing: JPRT, TestOptionsWithRanges.java via RBT and manual test as CR
>>> description.
>>>
>>> Thanks,
>>> Sangheon
>>>
>>>
>>>
>