CPU differences and CMS GC performance

Jon Masamitsu jon.masamitsu at oracle.com
Thu Jan 6 21:09:27 UTC 2011


Craig,

I looked at the heap occupancy in the first ParNew collection after the 
CMS sweep
and it looks like there is about 1.36g of live data for the old server 
(for example
from the first entry below)

2011-01-04T18:41:13.786-0500: 317421.837: [GC 317421.838: [ParNew: 693227K->86037K(757760K), 0.1202290 secs]
1969847K->1363829K(2408448K), 0.1209860 secs] [Times: user=0.60
sys=0.00, real=0.12 secs]

In the new server the number looks more like 1.46g

2011-01-04T18:41:40.336-0500: 224473.169: [GC 224473.170: [ParNew: 
757760K->151551K(757760K), 0.1246970 secs] 2061601K->1458549K(2408448K), 
0.1250470 secs] [Times: user=0.67 sys=0.00, real=0.13 secs]

*Maybe your application has a higher throughput on the new server
and has more live data in flight.  If you think that might be true a
larger heap would help.

You should verify what I've seen from these snippets.  Or better yet if you
have a way of telling how much data the application is using at any 
particular
instant and that number is larger on the new server, then use
a larger heap.

Jon*

On 01/06/11 11:45, craig yeldell wrote:
> 2011-01-04T18:40:57.595-0500: 317405.646: [CMS-concurrent-reset: 
> 0.060/0.060 secs] [Times: user=0.06 sys=0.00, real=0.06 secs]
> 2011-01-04T18:41:13.786-0500: 317421.837: [GC 317421.838: [ParNew: 
> 693227K->86037K(757760K), 0.1202290 secs] 
> 1969847K->1363829K(2408448K), 0.1209860 secs] [Times: user=0.60 
> sys=0.00, real=0.12 secs]
> 2011-01-04T18:41:55.496-0500: 317463.548: [GC 317463.548: [ParNew: 
> 692245K->72000K(757760K), 0.1097190 secs] 
> 1970037K->1351019K(2408448K), 0.1104820 secs] [Times: user=0.55 
> sys=0.00, real=0.11 secs]
> 2011-01-04T18:42:16.564-0500: 317484.615: [GC 317484.616: [ParNew: 
> 678208K->77171K(757760K), 0.1477570 secs] 
> 1957227K->1356301K(2408448K), 0.1485110 secs] [Times: user=0.65 
> sys=0.00, real=0.15 secs]
> 2011-01-04T18:42:36.084-0500: 317504.135: [GC 317504.136: [ParNew: 
> 683379K->95237K(757760K), 0.1488350 secs] 
> 1962509K->1378558K(2408448K), 0.1496090 secs] [Times: user=0.75 
> sys=0.00, real=0.15 secs]
> 2011-01-04T18:43:05.470-0500: 317533.521: [GC 317533.522: [ParNew: 
> 701445K->78163K(757760K), 0.1416930 secs] 
> 1984766K->1362521K(2408448K), 0.1424460 secs] [Times: user=0.71 
> sys=0.00, real=0.15 secs]
> 2011-01-04T18:43:45.488-0500: 317573.540: [GC 317573.540: [ParNew: 
> 684371K->77448K(757760K), 0.1396650 secs] 
> 1968729K->1363169K(2408448K), 0.1404410 secs] [Times: user=0.64 
> sys=0.00, real=0.14 secs]
> 2011-01-04T18:44:23.197-0500: 317611.249: [GC 317611.249: [ParNew: 
> 683656K->101827K(757760K), 0.1286880 secs] 
> 1969377K->1387892K(2408448K), 0.1295040 secs] [Times: user=0.64 
> sys=0.00, real=0.13 secs]
> 2011-01-04T18:45:03.946-0500: 317651.997: [GC 317651.998: [ParNew: 
> 708035K->82138K(757760K), 0.1496900 secs] 
> 1994100K->1368999K(2408448K), 0.1504710 secs]
>
>
> On Jan 6, 2011, at 10:53 AM, Jon Masamitsu wrote:
>
>> 2011-01-04T18:40:57
>
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