RFR(S): 8025227: Add -XX: flag to print code cache sweeper statistics

[Vladimir Kozlov]

I agree with Chris, we are collecting those counters anyway. I also like 
Chris's idea about collecting freed sizes. Note, some counters will be 
removed by 8020151 changes:

http://cr.openjdk.java.net/~anoll/8020151/webrev.03/

Thanks,
Vladimir

On 9/26/13 2:13 PM, Chris Plummer wrote:
> Hi Tobias,
>
> The one comment I would have is that the statistics you produce are all
> timing related, but the option name implies you would get a bit more
> than this. For example, maybe something like a count of the number of
> methods flushed (and maybe total size). So I would suggest either rename
> to PrintMethodFlushingTimingStatistics (and also rename the print
> method), or add some other useful statistics to the output. Probably all
> the counters located below the " Stat counters" comment are good candidates.
>
> best regards,
>
> Chris
>
> On 9/25/13 12:20 AM, Tobias Hartmann wrote:
>> Hi,
>>
>> Please review the following small patch.
>>
>> bug:�https://bugs.openjdk.java.net/browse/JDK-8025277
>> webrev:�http://cr.openjdk.java.net/~anoll/8025277/webrev.00/
>> <http://cr.openjdk.java.net/%7Eanoll/8025277/webrev.00/>
>>
>> I added the diagnostic VM option�PrintMethodFlushingStatistics to
>> print statistics about the NMethodSweeper (sweep times) on exit. This
>> is useful to determine performance bottlenecks of applications that
>> heavily compile code (e.g. nashorn).
>>
>> Thanks in advance!
>>
>> Best regards,
>> Tobias
>>
>>
>> By the way, I'm Tobias Hartmann, a student from Switzerland currently
>> working on my Master Thesis "Code Cache Optimizations for Dynamically
>> Compiled Languages" on supervision of Albert Noll.
>>
>>
>