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

[Christian Thalinger]

I've already pointed this out to Albert but before we can accept your contributions you need to sign the OCA.  See:

http://openjdk.java.net/contribute/

On Sep 27, 2013, at 7:39 AM, Tobias Hartmann <tobi.hartmann at gmail.com> wrote:

> Chris, Vladimir, thank you for your reviews. 
> I followed your suggestions and added other useful statistics. The output now looks like this:
> 
> Method flushing statistics:
>   Total sweep time: 152.649ms
>   Peak sweep time: 15.979ms
>   Peak sweep fraction time: 3.209ms
>   Total number of stack traversals: 25
>   Total number of flushed methods: 1320
>   Total size of flushed methods: 7188Kb
> 
> I did not include the other values, because as Vladimir already said, they are removed by 8020151.
> 
> Here is the new webrev:
> http://cr.openjdk.java.net/~anoll/8025277/webrev.01/
> 
> Thanks again for your review.
> 
> Regards,
> Tobias
> 
> 
> 
> 
> 2013/9/27 Vladimir Kozlov <vladimir.kozlov at oracle.com>
> 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.
> 
> 
> 
> 

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