RFR: 8059066: CardTableModRefBS might commit the same page twice

Thomas Schatzl thomas.schatzl at oracle.com
Wed Nov 26 10:49:42 UTC 2014


Hi,

On Tue, 2014-11-25 at 10:17 +0100, Erik Helin wrote:
> On 2014-11-24, Kim Barrett wrote:
> > On Nov 24, 2014, at 11:09 AM, Erik Helin <erik.helin at oracle.com> wrote:
> > > also added an assert to
> > > how that new_end_aligned <= _committed[ri].end() always is true.
> > 
> > Based on your earlier analysis about there being at most one
> > overlapping page, I think a tighter assertion could be used, e.g.
> > something like
> > 
> > new_end_aligned <= (HeapWord*)align_ptr_up(_committed[ri].start() + 1, _page_size)
> > 
> > That would definitely deserve a comment though, and I'm not sure it
> > adds enough to be worthwhile.
> > 
> > I looked a bit further down in the file, and initially worried about
> > the uncommit case messing things up, but I think it shouldn't be
> > possible for a committed region to have zero size because the
> > associated covered region never has zero size.
> > 
> > > Please
> > > see new webrevs at:
> > > - full: http://cr.openjdk.java.net/~ehelin/8059066/webrev.01/index.html
> > > - inc:  http://cr.openjdk.java.net/~ehelin/8059066/webrev.00-01/index.html
> > 
> > Looks good to me.
> 

Looks good.

Thomas




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