RFR: 8036703: Add trace event with statistics for the metaspace chunk free lists

[Coleen Phillimore]

Wow, that looks good.   The only comment I had was that this macro for 
index index_bounds_check in metaspace.cpp could be an inlined static 
function, then you could avoid the odd while loop.

Coleen

On 3/12/14 12:04 PM, Erik Helin wrote:
> Based on feedback from Mikael and StefanK, I've reworked the patch to 
> put the ChunkFreeListSummaries in the class MetaspaceSummary.
>
> Please see the new version at:
> http://cr.openjdk.java.net/~ehelin/8036703/webrev.03/
>
> Thanks,
> Erik
>
> On 2014-03-06 11:56, Erik Helin wrote:
>> A small bug had found its way into this patch:
>>
>> metaspace.cpp:
>> +bool MetaspaceAux::has_chunk_free_list(Metaspace::MetadataType 
>> mdtype) {
>> +  return Metaspace::get_chunk_manager(mdtype) == NULL;
>> +}
>>
>> should of course be:
>>
>> +bool MetaspaceAux::has_chunk_free_list(Metaspace::MetadataType 
>> mdtype) {
>> +  return Metaspace::get_chunk_manager(mdtype) != NULL;
>> +}
>>
>> Please see new webrev at:
>> http://cr.openjdk.java.net/~ehelin/8036703/webrev.01/
>>
>> Thanks,
>> Erik
>>
>> On 2014-03-06 10:35, Erik Helin wrote:
>>> Hi all,
>>>
>>> this patch adds a new trace event -
>>> vm/gc/metaspace/chunk_free_list_summary for getting statistics for
>>> metaspace's chunk free lists. The event contains the numbers of chunks
>>> in the free list and the size of the chunks in the free lists. This
>>> information is provided for all different kinds of chunks - special,
>>> small, medium and humongous.
>>>
>>> This information will be useful when diagnosing fragmentation issues in
>>> metaspace.
>>>
>>> Webrev:
>>> http://cr.openjdk.java.net/~ehelin/8036703/webrev.00/
>>>
>>> Enhancement:
>>> https://bugs.openjdk.java.net/browse/JDK-8036703
>>>
>>> Testing:
>>> - JFR JTREG tests
>>> - JPRT
>>> - Manually verifying that the numbers look correct by looking at
>>>    recordings from small test cases.
>>>
>>> Thanks,
>>> Erik