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Hi John,<br>
<br>
Thanks a lot for looking at the change again and the field
compressing suggestion! I've looked into the FieldInfo array and
optimized the memory usage for the generic signature index slot
earlier this year. I haven't played with any compression technique.
Thanks for the suggestion, definitely worth to look into. I have one
question maybe you have quick answer to it. Does C1 or C2 heavily
relying on fast accessing to the FieldInfo array?<br>
<br>
Thanks,<br>
<br>
Jiangli<br>
<br>
On 12/10/2012 03:10 PM, John Rose wrote:
<blockquote
cite="mid:0AABC510-5CDE-4C98-9DC4-DEE7183AA1CD@oracle.com"
type="cite">
<div>
<div>On Dec 9, 2012, at 9:53 PM, Jiangli Zhou wrote:</div>
<br class="Apple-interchange-newline">
<blockquote type="cite">
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<div text="#000000" bgcolor="#ffffff"> Hi John,<br>
<br>
Here is the updated webrev with Address constant change in
where it's appropriate: <br>
<br>
<a moz-do-not-send="true" class="moz-txt-link-freetext"
href="http://cr.openjdk.java.net/%7Ejiangli/8004076/webrev.01/">http://cr.openjdk.java.net/~jiangli/8004076/webrev.01/</a>.
<br>
<br>
I'm also double checking with jprt and runthese tests.<br>
</div>
</blockquote>
</div>
<br>
<div>Yes, that's much nicer; thanks.</div>
<div><br>
</div>
<div>Has your group been considering compressing the field
metadata (type FieldInfo)?</div>
<div><br>
</div>
<div>I think that, by using a variable-length byte-oriented
format, we could easily cut the size of that data by more than
50%.</div>
<div><br>
</div>
<div>The initval field and the high part of the offset are almost
always zero. The number of access flags configurations is very
small, much smaller than 2**16. (Low entropy everywhere!) All
this means they could be profitably cut out most of the time
with profit, as long as the access method does not slow the VM
down detectably.</div>
<div><br>
</div>
<div>I'm thinking about this because of Alexey's work on
@Contended and the upcoming work on @Stable. Also, if we do
field profiling we may need to add miscellaneous bits to the
field metadata.</div>
<div><br>
</div>
<div>— John</div>
</blockquote>
<br>
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