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Hi Everyone,<br>
<br>
I have a new webrev based upon comments from Tony, which can be found
at: <a class="moz-txt-link-freetext" href="http://cr.openjdk.java.net/~johnc/7119908/webrev.1/">http://cr.openjdk.java.net/~johnc/7119908/webrev.1/</a><br>
<br>
Changes in this version include:<br>
<br>
* Using the value of the existing G1CollectedHeap::_gc_time_stamp
field, rather than the value of _total_collections, as the TS values.<br>
* A small optimization that may reduce the number of iterations while
walking the collection set to calculate the starting region for a
worker. We check the entry for the previous worker and if that is valid
then we starting iterating over the collection set from that region.<br>
<br>
Testing:<br>
GC test suite; jprt.<br>
<br>
Thanks,<br>
<br>
JohnC<br>
<br>
On 12/09/11 11:18, John Cuthbertson wrote:
<blockquote cite="mid:4EE25EFE.9090902@oracle.com" type="cite">
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Hi Everyone,<br>
<br>
Can I have a couple of volunteers to review the changes for this CR?
The webrev can be found at: <a moz-do-not-send="true"
class="moz-txt-link-freetext"
href="http://cr.openjdk.java.net/%7Ejohnc/7119908/webrev.0/">http://cr.openjdk.java.net/~johnc/7119908/webrev.0/</a><br>
<br>
Summary:<br>
As part of the code review comments for 7112743 (G1: Reduce overhead of
marking closure during evacuation pauses) it was suggested that instead
of recalculating the starting heap region for each worker thread, we
reuse the values calculated during RSet scanning. These changes address
that review comment. In these changes I maintain a cache that is used
and updated by G1CollectedHeap::start_cset_region_for_worker(). The
first time this routine is called by a worker thread during an
evacuation pause (currently during RSet scanning) the cached value for
the worker gets set; when the routine is called subsequently the region
that was cached for the worker is returned. I employ a simple stamp
mechanism based upon the number of GCs that ensures the validity of the
regions in the cache and makes clearing the cache unnecessary.<br>
<br>
Testing:<br>
GC Test suite with a small marking threshold (10%) with and without
verification; the configuration of SPECjbb used to test 7117423;
Kitchensink.<br>
<br>
Thanks,<br>
<br>
JohnC<br>
<br>
</blockquote>
<br>
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