RFR (S): 8079091: Remove dictionary NULL check on common path of BlockFreeList methods

[Srinivas Ramakrishna]

Hi Jungwoo --

Xalan most definitely shows a huge improvement. Could you rerun your
numbers with the latest version of your diffs and see if the numbers
reproduce and, if so, perhaps indicate why the numbers improve so much for
Xalan?

thanks!
-- ramki

On Wed, Apr 29, 2015 at 10:22 PM, Jungwoo Ha <jwha at google.com> wrote:

> The slower ones have higher error bars (error bars are 95% confidence
> interval), and you can see that those are not statistically significant.
> I'll reflect your suggestions and upload the new webrev.
>
> On Wed, Apr 29, 2015 at 10:00 PM, Kim Barrett <kim.barrett at oracle.com>
> wrote:
>
> > On Apr 29, 2015, at 7:34 PM, Jungwoo Ha <jwha at google.com> wrote:
> > >
> > > BUG: https://bugs.openjdk.java.net/browse/JDK-8079091
> > > Webrev: http://cr.openjdk.java.net/~jwha/8079091/webrev.00/
> > >
> > > Can someone sponsor this change?
> > > I've seen ~3% speed up on DaCapo benchmarks. (results attached on the
> bug
> > > page.)
> >
> > Wow!
> >
> > Hm.  There are a couple of benchmarks that are a little bit slower.  I
> > don't know enough about that suite of benchmarks to know how important
> > that might be.
> >
> > Since the dictionary is always being created at construction time, the
> > null check in ~BlockFreelist is no longer needed either.
> >
> > It seems like a further improvement might be obtained by making the
> > dictionary a direct member subobject of BlockFreelist, rather than
> > allocating it as a separate object, thereby eliminating an
> > indirection.
> >
> > Pre-existing: Why is there a cast in SpaceManager::block_freelists()?
> >
> > Pre-existing: I found the private BlockFreelist::dictionary() member
> > function distracting rather than helpful, and would have preferred
> > just using the private data member directly. But maybe that's just me.
> > If _dictionary is changed to a subobject rather than a pointer, I'd
> > suggest changing a bunch of "dictionary()->XXX" to "_dictionary.XXX".
> >
> >
>