(resend) Request for review (S): 7068625 Testing 8 bytes of card table entries at a time speeds up card-scanning
bengt.rutisson at oracle.com
Fri Feb 24 12:53:19 UTC 2012
On 2012-02-24 13:50, Jesper Wilhelmsson wrote:
> I can have a look at it but I don't have the time to do it today. If
> Monday is OK then I can take it.
Will also need a second review from someone with OpenJDK reviewer status.
> 24 feb 2012 kl. 13:14 skrev Bengt Rutisson <bengt.rutisson at oracle.com
> <mailto:bengt.rutisson at oracle.com>>:
>> Hi all,
>> Just pinging this review request. Does anybody have some time to look
>> at it? It is a fairly small and straight forward change...
>> -------- Original Message --------
>> Subject: Request for review (S): 7068625 Testing 8 bytes of card
>> table entries at a time speeds up card-scanning
>> Date: Tue, 21 Feb 2012 12:03:50 +0400
>> From: Alexey Ragozin <alexey.ragozin at gmail.com>
>> To: hotspot-gc-dev at openjdk.java.net
>> CC: Bengt Rutisson <bengt.rutisson at oracle.com>
>> I would like few volunteers to review changes for
>> WebRev: http://cr.openjdk.java.net/~brutisso/7068625/webrev.00/
>> Change summary
>> For large heaps (I was focusing on 8GiB and above) it is common to
>> have long continuous ranges of clean cards.
>> Patch is introducing a short path for skipping ranges of clean cards
>> using word aligned memory access instead of byte aligned.
>> Patch affects serial and CMS collectors. For CMS collector stride
>> size should be increase to see any performance gains (I was using
>> For testing I was mainly using synthetic benchmark randomly modifying
>> hash tables in heap, thus uniformly touching cards across heaps.
>> Average duration of young GC pause were used as KPI.
>> More details about testing can be found at
>> Though article is referring jdk6, my resent tests with trunk jdk7
>> show no difference.
>> I was also tested patch with real application (Oracle Coherence
>> storage node).
>> With 16GiB of heap and CMS/ParNew GC, enabling patch have shortened
>> GC pauses roughly in 2 times.
>> Source code of benchmark used in test are available at
>> Main class YoungGCPauseBenchmark
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