gc log analysis tools
Jon.Masamitsu at Sun.COM
Fri Oct 26 07:54:37 UTC 2007
It's typical to see lower performance with the 64bit VM. A drop of 23%
seems a little high
but is in the ball park. The drop in performance comes from the
increased memory traffic
due to the larger objects.
Hope that helps.
PS. I don't think the output from -verbosegc changed at all between jdk
1.4.2 and jdk 5.
If it did, I think the change was very minor. One difference you might
see with jdk 5 is that
you could be getting a different default garbage collector. That might
be the source of
differences in the logs you're trying to analyze.
Ben Cheng wrote:
> The reason I am interested in this information is because I have a
> benchmark whose score is X using 32-bit VM and 2G of heap. When I
> switched to 64-bit build of the same VM, the score dropped to 0.77X
> with the same amount of heap. If I increase the heap size to 3.5G (on
> a machine with 4GB of RAM), the score went to to 1.40X.
> What I need is pretty basic - it sums up all the gc time from the
> verbose log during a benchmark run, as I want to verify if the change
> in gc time correlates to the change in performance. I can write a
> similar script to do that, but I just want to check to see if there is
> a working tool out there already. Apparently the verbose gc log format
> changed from 1.5 and beyond and the old script is not compatible.
> On 10/25/07, * Neo Jia* <neojia at gmail.com <mailto:neojia at gmail.com>>
> What is your opion? I had one but not sure if it would work for
> you or not (
> I have not worked on JDK for a while ...
> On 10/25/07, Ben Cheng < bccheng at google.com
> <mailto:bccheng at google.com>> wrote:
> > Hi,
> > I was trying to get a sense of total GC time spent in a Java app
> using 1.6
> > JDK. The gc logs (w/ and wo/ parallel gc) seem to break the
> ancient tool
> > gc_analyze.pl found on the web.
> > Is there an update to date tool to produce the desired
> information for new
> > JDKs?
> > Thanks in advance,
> > -Ben
> I would remember that if researchers were not ambitious
> probably today we haven't the technology we are using!
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