Request for review: 7098155: Resize young gen at full collections for UseParallelGC

Tao Mao tao.mao at oracle.com
Mon Sep 23 16:13:19 PDT 2013


Hi,

changeset:
https://bugs.openjdk.java.net/browse/JDK-7098155

In order to avoid the situation for UseParallelGC described in the CR, 
we need to resize young gen at full collections.

And, according to the heap configuration in young gen, we need to swap 
from- and to-space () after full gc in order to get the young gen 
correctly resized after several GC's.

webrev:
http://cr.openjdk.java.net/~tamao/7098155/webrev.00/

test:
- Pass JPRT tests

- RefWorkload

(1) ParallelGC (-XX:+UseParallelGC -XX:-UseParallelOldGC)

baseline:  -XX:-UseAdaptiveSizePolicyResizeYoungGenAtMajorCollection
resize:     -XX:+UseAdaptiveSizePolicyResizeYoungGenAtMajorCollection

./compare results_baseline_512m results_resize_512m
==============================================================================
results_baseline_512m:
   Benchmark           Samples        Mean     Stdev             Geomean 
Weight
   jetstream                30      192.52      9.86
   scimark                  30      855.62     30.33
   specjbb2005              30   145844.73   4552.07
   specjvm98                30      568.92     10.65
==============================================================================
results_resize_512m:
   Benchmark           Samples        Mean     Stdev   %Diff     P  
Significant
   jetstream                30      192.89     11.33    0.19 
0.894            *
   scimark                  30      862.21     24.17    0.77 
0.356            *
   specjbb2005              30   142749.53   4852.66   -2.12 
0.014            *
   specjvm98                30      566.42      8.55   -0.44 
0.320            *
==============================================================================
   * - Not Significant: A non-zero %Diff for the mean could be noise. If the
       %Diff is 0, an actual difference may still exist. In either case, 
more
       samples would be needed to detect an actual difference in sample 
means.

(2) ParallelOldGC (-XX:+UseParallelGC -XX:+UseParallelOldGC)

baseline:  -XX:-UseAdaptiveSizePolicyResizeYoungGenAtMajorCollection
resize:     -XX:+UseAdaptiveSizePolicyResizeYoungGenAtMajorCollection

./compare results_baseline_512m_ParallelOldGC 
results_resize_512m_ParallelOldGC
==============================================================================
results_baseline_512m_ParallelOldGC:
   Benchmark           Samples        Mean     Stdev             Geomean 
Weight
   jetstream                30      196.15      8.91
   scimark                  30      855.92     22.58
   specjbb2005              30   161857.59   2653.89
   specjvm98                30      554.76     11.31
==============================================================================
results_resize_512m_ParallelOldGC:
   Benchmark           Samples        Mean     Stdev   %Diff     P  
Significant
   jetstream                30      195.17      6.04   -0.50 
0.623            *
   scimark                  30      853.43     22.33   -0.29 
0.669            *
   specjbb2005              30   161027.44   2705.23   -0.51 
0.235            *
   specjvm98                30      560.08      9.74    0.96 
0.056            *
==============================================================================
   * - Not Significant: A non-zero %Diff for the mean could be noise. If the
       %Diff is 0, an actual difference may still exist. In either case, 
more
       samples would be needed to detect an actual difference in sample 
means.

Thanks.
Tao


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