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Please see inline.<br>
<br>
Thanks.<br>
Tao<br>
<br>
On 5/30/13 5:53 AM, Bengt Rutisson wrote:
<blockquote cite="mid:51A74BBC.7070003@oracle.com" type="cite">
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Hi Tao,<br>
<br>
I think the code is a little bit confused about whether
G1MultiParGCAllocBuffer can handle an arbitary number of
AllocPriorites or just 2. All the for loops indicate that we
think we might want to change from 2 to a larger number in the
future. But the naming of a method like
words_remaining_in_retired() indicate that there can only be one
retired region. With the current implementation I think
words_remaining_in_retired() should be called something like
words_remaining_in_priority0_buffer(). <br>
</div>
</blockquote>
Done.<br>
changed to words_remaining_in_priority1_buffer()<br>
<blockquote cite="mid:51A74BBC.7070003@oracle.com" type="cite">
<div class="moz-cite-prefix"> <br>
I think it would be good to make this code truly general with
respect to the number of priorities. We can then use 2 as
default, but make sure that the code works with more priorities.
To do that I think we should remove the enum GCAllocPriority and
instead have a field in G1MultiParGCAllocBuffer that contains
the maximum number of priorities. I think that will make the
code more general and easier to read. The for loops would look
like:<br>
<br>
for (int pr = 0; pr < _max_priorities; ++pr) {<br>
// do stuff<br>
}<br>
</div>
</blockquote>
It's more like code style issue. In fact, it was done this way
according to the Jon's earlier suggestion. Second, if we want to
change #buffer to 3 (it wont give more benefits to define more than
that number), we only need to add one more enum value, i.e.
GCAllocPriority3.<br>
<blockquote cite="mid:51A74BBC.7070003@oracle.com" type="cite">
<div class="moz-cite-prefix"> <br>
I find the name G1MultiParGCAllocBuffer confusing since it is
not inheriting G1ParGCAllocBuffer. Maybe G1AllocBufferContainer
or something like that would make more sense? <br>
</div>
</blockquote>
Done. <br>
Changed to G1ParGCAllocBufferContainer
<blockquote cite="mid:51A74BBC.7070003@oracle.com" type="cite">
<div class="moz-cite-prefix"> <br>
I don't understand why you added initialization values to
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GCAllocPurpose. You are only using the values that are default
in C++ anyway: 0, 1, 2. At least if you avoid adding the
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GCAllocPurposeStart value. I think it was more readable before
your change. (The same argument holds for GCAllocPriority, but I
prefer to remove that enum all together as I described above.)<br>
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See above.<br>
<blockquote cite="mid:51A74BBC.7070003@oracle.com" type="cite">
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Have you considered moving the _retired field from
G1ParGCAllocBuffer to ParGCAllocBuffer instead of making the
retire() method virtual? (I do think your change to virtual is
needed in the current code, so good catch! But I think it might
make sense to have the logic of G1ParGCAllocBuffer::retire() in
ParGCAllocBuffer::retire() instead.)<br>
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</blockquote>
In G1ParGCAllocBuffer, we need the field _retired to handle buffer
allocation failure. This is handled differently for other
collectors. For example, ParScanThreadState::alloc_in_to_space_slow
in ParNew. Thus, moving the _retired field up to its super class
will involve additional efforts. This is supposed to be investigated
in another CR JDK-7127700.<br>
<blockquote cite="mid:51A74BBC.7070003@oracle.com" type="cite">
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A couple of minor things:<br>
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1800 if (finish_undo != true) ShouldNotReachHere();<br>
<br>
should be:<br>
<br>
1800 if (!finish_undo) ShouldNotReachHere();<br>
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Done.<br>
<blockquote cite="mid:51A74BBC.7070003@oracle.com" type="cite">
<div class="moz-cite-prefix"> <br>
Please add spaces before and after "=" here:<br>
1804 size_t result=0;<br>
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Done.<br>
<blockquote cite="mid:51A74BBC.7070003@oracle.com" type="cite">
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There are two spaces after "=" here:<br>
1812 G1ParGCAllocBuffer* retired =
_priority_buffer[GCAllocPriority1];<br>
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Done.<br>
<blockquote cite="mid:51A74BBC.7070003@oracle.com" type="cite">
<div class="moz-cite-prefix"> <br>
Also, in g1CollectedHeap.hpp you have updated the copyright year
but not in parGCAllocBuffer.hpp. As you know we in the GC team
have agreed not to update the copyright year. If you absolutely
want to do it I think you should do it the same way in all
files.<br>
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Done.<br>
<blockquote cite="mid:51A74BBC.7070003@oracle.com" type="cite">
<div class="moz-cite-prefix"> <br>
Thanks,<br>
Bengt<br>
<br>
On 5/24/13 1:31 AM, Tao Mao wrote:<br>
</div>
<blockquote cite="mid:519EA6EA.1080308@oracle.com" type="cite">Can
I have a couple of reviewers please? <br>
<br>
Thank you. <br>
Tao <br>
<br>
On 5/20/13 5:11 PM, Tao Mao wrote: <br>
<blockquote type="cite">Hi all, <br>
<br>
a new webrev <br>
<a moz-do-not-send="true" class="moz-txt-link-freetext"
href="http://cr.openjdk.java.net/%7Etamao/6976350/webrev.04/">http://cr.openjdk.java.net/~tamao/6976350/webrev.04/</a>
<br>
<br>
diff: <br>
(1) John Cuthbertson and I figured out the way to handle
"retire an old buffer, allocate and set a new one" and it can
possibly make the usage of allocation buffer a little more
efficient. <br>
(2) Make the assertion as John suggested and provide some
harness (i.e. making retire() a virtual function) to cope with
it. <br>
<br>
Thanks. <br>
Tao <br>
<br>
On 5/15/13 10:58 PM, John Cuthbertson wrote: <br>
<blockquote type="cite">Hi Tao, <br>
<br>
This looks excellent. One minor question: does it make sense
to assert that each buffer has been retired? It might save a
missed call to PSS::retire_alloc_buffers. I'll leave the
decision to you. Ship it. <br>
<br>
JohnC <br>
<br>
<br>
On 5/14/2013 3:06 PM, Tao Mao wrote: <br>
<blockquote type="cite">To the open list: <br>
<br>
new webrev: <br>
<a moz-do-not-send="true" class="moz-txt-link-freetext"
href="http://cr.openjdk.java.net/%7Etamao/6976350/webrev.03/">http://cr.openjdk.java.net/~tamao/6976350/webrev.03/</a>
<br>
<br>
I took suggestion from many reviewers into consideration
and came up with the current cleaner solution. <br>
<br>
Thank you. <br>
Tao <br>
<br>
<br>
On 5/14/13 2:26 PM, Jon Masamitsu wrote: <br>
<blockquote type="cite">What's the status of this review?
<br>
<br>
The last mail I could find in my mail boxes was a
comment <br>
from Thomas. <br>
<br>
Jon <br>
<br>
On 1/28/13 12:21 PM, Tao Mao wrote: <br>
<blockquote type="cite">6976350 G1: deal with
fragmentation while copying objects during GC <br>
<a moz-do-not-send="true"
class="moz-txt-link-freetext"
href="https://jbs.oracle.com/bugs/browse/JDK-6976350">https://jbs.oracle.com/bugs/browse/JDK-6976350</a>
<br>
<br>
webrev: <br>
<a moz-do-not-send="true"
class="moz-txt-link-freetext"
href="http://cr.openjdk.java.net/%7Etamao/6976350/webrev.00/">http://cr.openjdk.java.net/~tamao/6976350/webrev.00/</a>
<br>
<br>
changeset: <br>
Basically, we want to reuse more of par-allocation
buffers instead of retiring it immediately when it
encounters an object larger than its remaining part. <br>
<br>
(1) instead of previously using one allocation buffer
per GC purpose, we use N(=2) buffers per GC purpose
and modify the corresponding code. The changeset would
easily scale up to whatever N (though Tony Printezis
suggests 2, or 3 may be good enough) <br>
<br>
*(2) Two places of cleanup: allocate_during_gc_slow()
is removed due to its never being called. <br>
access
modifier (public) before trim_queue() is redundant. <br>
<br>
<br>
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