RFR(S): JDK-8047330: Remove unrolled card loops in G1 SparsePRTEntry

Andreas Sjöberg andreas.sjoberg at oracle.com
Wed Jun 25 07:02:26 UTC 2014


Following Mikael's review and some offline comments from Thomas I've 
made these changes in addition to removing the unrolled card loops:

* removed the now unused define
* added braces for the for-loop in SparsePRTEntry::init
* changed the implementation of copy_cards to use memcpy

New webrev: http://cr.openjdk.java.net/~jwilhelm/8047330/webrev.02/


On 06/23/2014 04:51 PM, Mikael Gerdin wrote:
> Hi Andreas,
> On Thursday 19 June 2014 15.27.23 Andreas Sjöberg wrote:
>> Hi all,
>> can I please have reviews for this patch that removes the unrolled
>> for-loops in sparsePRT.cpp.
>> I ran some performance benchmarks and could not see any benefits in
>> keeping the unrolled for loops. SPECjbb2013 shows a 3.48% increase on
>> Linux x64 actually.
>> Webrev: http://cr.openjdk.java.net/~jwilhelm/8047330/webrev/
> It looks like you can remove the define as well:
>    36 #define UNROLL_CARD_LOOPS  1
> UnrollFactor should also be useless now, but it seems like it's being used to
> align up the number of cards. I suggest you leave UnrollFactor for a second
> cleanup.
> /Mikael
>> Testing: jprt, specjbb2005, specjvm2008, specjbb2013
>> Thanks,
>> Andreas

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