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<div class="moz-cite-prefix">On 2/25/16 9:46 AM, Mikael Gerdin
wrote:<br>
</div>
<blockquote cite="mid:56CF13AB.20202@oracle.com" type="cite">Hi all,
<br>
<br>
The G1 Young RemSet Sampling Thread iterates over the young
regions to estimate the remembered set sizes of the young gen in
order to tweak the young gen size between gcs.
<br>
<br>
All the iteration and the state related to this has been stored in
the YoungList class for some strange reason. The state is actually
only ever needed in
G1YoungRemSetSamplingThread::sample_young_list_rs_lengths()
<br>
so I've moved all of it there.
<br>
I also modified revise_young_list_target_length_if_necessary to
receive the new rs length sample as a parameter instead of picking
it up from the YoungList class.
<br>
<br>
Bug: <a class="moz-txt-link-freetext" href="https://bugs.openjdk.java.net/browse/JDK-8150390">https://bugs.openjdk.java.net/browse/JDK-8150390</a>
<br>
Webrev: <a class="moz-txt-link-freetext" href="http://cr.openjdk.java.net/~mgerdin/8150390/webrev.0">http://cr.openjdk.java.net/~mgerdin/8150390/webrev.0</a>
<br>
Testing: Local GC test suite and JPRT
<br>
<br>
Thanks
<br>
/Mikael
<br>
</blockquote>
Much cleaner!<br>
<br>
Some questions:<br>
-
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In G1YoungRemSetSamplingThread::sample_young_list_rs_lengths(), if
we yield we now return directly and don't call <span
class="changed">revise_young_list_target_length_if_necessary(),
but before we would call it, even though data might be incomplete.
Is this the right choice? (It sounds reasonable to me, but I can't
prove it).<br>
<br>
- That code around the yield is very conservative. Maybe a GC
occurred, or maybe not. Can't we tell if it did or not, and only
bail out then? Yes, this is a pre-existing issue :-)<br>
<br>
- Derek<br>
<br>
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