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| lancelotlinc |
 Posted: Mon Feb 14, 2011 7:57 am Post subject: WMB support of AIX 7.1 Terabyte segment |
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Jedi Knight
Joined: 22 Mar 2010
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| mqjeff |
| Posted: Mon Feb 14, 2011 8:07 am Post subject: |
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Grand Master
Joined: 25 Jun 2008
Posts: 17447
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Is AIX 7.1 listed as supported for broker 7?
Is that JVM limitation for a Java 1.5 JVM? Broker v7 uses Java 1.6, not 1.5. |
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| WMBDEV1 |
| Posted: Mon Feb 14, 2011 8:35 am Post subject: Re: WMB support of AIX 7.1 Terabyte segment |
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Sentinel
Joined: 05 Mar 2009
Posts: 888
Location: UK
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| lancelotlinc wrote: |
| Except that on AIX, the max heap for the JRE can only be 64 MB because of the JRE limitation. |
I didnt see that particular extract from the link provided.... What I read was:
"The maximum heap size is controlled by the -Xmx option. If this option is not specified, the default applies as follows:
|AIX
|64 MB"
Can you provide the actual link that states your assertion?
If this was a maximum that would be some limit and i'm sure i've had much bigger objects on my java heap in AIX than that before! |
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| lancelotlinc |
| Posted: Mon Feb 14, 2011 8:38 am Post subject: |
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Jedi Knight
Joined: 22 Mar 2010
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Location: Bloomington, IL USA
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That limit was for JRE 5, sorry. JRE 6 Diagnotics guide has some great verbiage on how the garbage collector works ( http://download.boulder.ibm.com/ibmdl/pub/software/dw/jdk/diagnosis/diag60.pdf ). For JRE 6, the max heap size on AIX is "Half the available memory with a minimum of 16 MB and a maximum of 512 MB."
WMB 7.x is supported on AIX 7.1 ( http://www-01.ibm.com/support/docview.wss?rs=849&uid=swg27017128 ). As you know, being supported on AIX 7.1 and fully utilizing the 7.1 Terabyte memory architecture are different.
I guess that drives to the heart of my question. What's the roadmap to enable WMB runtime's use of Terabyte segments. This would open a world of new performance possibilities for those parts that are native (ie. the C++ parts).
For the Java parts, they will still work, but are limited by the IBM JRE to 512 MB Heap. We would need a newer JRE that is enabled to take advantage of 1 Terabyte segments.
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| mqjeff |
| Posted: Mon Feb 14, 2011 8:52 am Post subject: |
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Grand Master
Joined: 25 Jun 2008
Posts: 17447
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| File a requirement or talk to your IBM Sales rep. That's the only way to get anything close to a statement of future direction. |
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| fjb_saper |
| Posted: Mon Feb 14, 2011 10:49 am Post subject: |
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Grand High Poobah
Joined: 18 Nov 2003
Posts: 20756
Location: LI,NY
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Don't know where you get the max heap of 512MB from... The pdf in the link states
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(page 22 IBM SDK for Java: Diagnostics Guide)
Maximum heap sizes
The typical maximum heap sizes are as follows:
Windows XP 32-bit on 32-bit hardware using the 32–bit JVM 1800 MiB old area and 1000 MiB new area.
-Xgc:splitheap -Xmx2800m -Xmox1800m
Windows XP 64-bit on 64-bit hardware using the 32–bit JVM 1700 MiB old area and 2000 MiB new area.
Allocate Space Survivor Space Allocate Space Survivor Space 50% 90%
-Xgc:splitheap -Xmx3700m -Xmox1700m
Applications have lower limits if they load a large number of classes, load a large
number of native libraries, or start several threads. |
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| lancelotlinc |
| Posted: Mon Feb 14, 2011 11:13 am Post subject: |
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Jedi Knight
Joined: 22 Mar 2010
Posts: 4941
Location: Bloomington, IL USA
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Windows max heap is 2 GB. AIX max heap is 512 MB according to Appendix E. Since the topic is AIX Terabyte segment support, I didn't consider the Windows parameters in my posting. Sorry. JRE Max heap seems to be platform dependent. (AIX is different than Windows.) If you have different info, please post. Maybe I'm not reading the doc correctly.
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| lancelotlinc |
| Posted: Mon Feb 14, 2011 11:27 am Post subject: |
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| fjb_saper |
| Posted: Mon Feb 14, 2011 11:27 am Post subject: |
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Grand High Poobah
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| lancelotlinc wrote: |
| Windows max heap is 2 GB. AIX max heap is 512 MB according to Appendix E. Since the topic is AIX Terabyte segment support, I didn't consider the Windows parameters in my posting. Sorry. JRE Max heap seems to be platform dependent. (AIX is different than Windows.) If you have different info, please post. Maybe I'm not reading the doc correctly. |
I get your point. I thought that this is looking also into native memory. As such I would have expected to get a max heap in the 2 GB size with paging as the native heap allocation is less. I was surprised to see that the Linux heap was no different from the AIX one. Well maybe not on the IBM JVM... 
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| mqjeff |
| Posted: Mon Feb 14, 2011 11:31 am Post subject: |
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Grand Master
Joined: 25 Jun 2008
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| Quote: |
| (Note: A long pause may occur while the garbage collector goes through the huge heap.) |
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| fjb_saper |
| Posted: Mon Feb 14, 2011 11:37 am Post subject: |
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Grand High Poobah
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That looks much more like what I was expecting... 
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| fjb_saper |
| Posted: Mon Feb 14, 2011 12:05 pm Post subject: |
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Grand High Poobah
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| mqjeff wrote: |
| Quote: |
| (Note: A long pause may occur while the garbage collector goes through the huge heap.) |
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Isn't that why you'd want to optimize garbage collection, and maybe use parallel garbage collection? Anyways collecting 1 EB of heap will sure take quite a bit longer than collecting 2 or 3 GB.
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