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<div class="moz-cite-prefix">On 6/5/13 7:05 PM, John Cuthbertson
wrote:<br>
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<blockquote cite="mid:51AF6FC8.5070501@oracle.com" type="cite">
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Hi Stefan,<br>
<br>
He wanted a power of two. <br>
</blockquote>
<br>
And the reason being?<br>
<br>
It won't help the cache alignment "issues" that Per talked about
earlier, if that's the reason. The array will still not be aligned
against a cache line size.<br>
<br>
Anyways, I'm happy with the change.<br>
<br>
StefanK<br>
<blockquote cite="mid:51AF6FC8.5070501@oracle.com" type="cite"> <br>
JohnC<br>
<br>
<div class="moz-cite-prefix">On 6/5/2013 4:10 AM, Stefan Karlsson
wrote:<br>
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<div class="moz-cite-prefix">On 06/04/2013 09:00 PM, John
Cuthbertson wrote:<br>
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<blockquote cite="mid:51AE3941.90609@oracle.com" type="cite">
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Hi Everyone,<br>
<br>
Here's a new webrev for this change: <a
moz-do-not-send="true" class="moz-txt-link-freetext"
href="http://cr.openjdk.java.net/%7Ejohnc/8015237/webrev.1">http://cr.openjdk.java.net/~johnc/8015237/webrev.1</a><br>
</blockquote>
<br>
Looks good. Thanks for doing all the cleanups.<br>
<br>
<blockquote cite="mid:51AE3941.90609@oracle.com" type="cite"> <br>
Changes from before:<br>
* Refactored the code that loops over the buckets into its own
routine.<br>
* Removed the commented out instrumentation (oops).<br>
* Changed the types to int to be consistent with the rest of
symbolTable and allow removal of the casts.<br>
* Increase the number of buckets per claim to 32 based upon a
verbal comment from John Coomes.<br>
</blockquote>
<br>
Care to describe the reasoning why 32 should be better?<br>
<br>
<blockquote cite="mid:51AE3941.90609@oracle.com" type="cite"> *
Removed the additional worker ID parameter for the sake of
peace and harmony.<br>
</blockquote>
<br>
Thanks.<br>
<br>
StefanK<br>
<br>
<blockquote cite="mid:51AE3941.90609@oracle.com" type="cite"> <br>
Testing: jprt.<br>
<br>
Thanks,<br>
<br>
JohnC<br>
<br>
<div class="moz-cite-prefix">On 5/24/2013 3:19 PM, John
Cuthbertson wrote:<br>
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<blockquote cite="mid:519FE787.70408@oracle.com" type="cite">
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Hi Everyone,<br>
<br>
Can I have a couple of reviewers look over these changes -
the webrev is: <a moz-do-not-send="true"
class="moz-txt-link-freetext"
href="http://cr.openjdk.java.net/%7Ejohnc/8015237/webrev.0/">http://cr.openjdk.java.net/~johnc/8015237/webrev.0/</a><br>
<br>
Summary:<br>
On some workloads we are seeing that the scan of the intern
string table (among others) can sometimes take quite a
while. This showed up on some FMW workloads with G1 where
the scan of the string table dominated the pause time for
some pauses. G1 was particularly affected since it doesn't
do class unloading (and hence pruning of the string table)
except at full GCs. The solution was to change the string
table from being considered a single root task and treat
similarly to the Java thread stacks: each GC worker claims a
given number of buckets and scans the entries in those
buckets.<br>
<br>
Testing<br>
Kitchensink; jprt; GC test suite. With all collectors.<br>
<br>
Overhead:<br>
Not real performance numbers but I did some measurement of
the synchronization overhead of using 1 GC worker thread.
They are summarized here:<br>
<br>
<table height="104" width="485" cellpadding="2"
cellspacing="2" border="1">
<tbody>
<tr>
<td valign="top"><br>
</td>
<td valign="top">0-threads (ms)<br>
</td>
<td valign="top">1-thread-chunked (ms)<br>
</td>
</tr>
<tr>
<td valign="top">Min</td>
<td valign="top">0.200<br>
</td>
<td valign="top">0.300<br>
</td>
</tr>
<tr>
<td valign="top">Max</td>
<td valign="top">6.900<br>
</td>
<td valign="top">8.800<br>
</td>
</tr>
<tr>
<td valign="top">Avg</td>
<td valign="top">0.658<br>
</td>
<td valign="top">0.794<br>
</td>
</tr>
</tbody>
</table>
<br>
These were from 1 hour long runs of Kitchensink with around
~2800 GCs in each run.<br>
<br>
Thanks,<br>
<br>
JohnC<br>
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