Solved

AME on AIX

Posted on 2014-03-18
5
662 Views
1 Endorsement
Last Modified: 2014-03-18
Advanced Memory expansion factor on my profile is set to "1", So technically no use, So what is the difference between turning it totally off Vs selecting AME with an expansion factor "1", What are performance implications. Please let me know..
1
Comment
Question by:aanya247
  • 3
  • 2
5 Comments
 
LVL 68

Accepted Solution

by:
woolmilkporc earned 500 total points
ID: 39937381
The AME factor is an indication of the expected target amount of increased memory.
If your LPAR has let's say 8 GB of memory then, with an AME factor of 2, the OS will report 16 GB of available memory nd the operating system will compress enough in-memory data to fit 16 GB of data into 8 GB of memory.

If you choose an AME factor which is too high there will be a memory deficit and the OS might have to page out virtual memory to page space. "amepat" will show if there is such a deficit.

An AME factor of 1 means that the operating system will not compress any memory.
It's the same as turning AME off, there's no difference.
0
 

Author Comment

by:aanya247
ID: 39937990
So there is no over head on the CPU if I set it to "1" ...??
0
 
LVL 68

Assisted Solution

by:woolmilkporc
woolmilkporc earned 500 total points
ID: 39938026
An AME factor of 1 effectively disables it. The remaining CPU overhead, if any, will be very, very low.

You can check the "Active Memory Expansion Statistics" section of "amepat -N" for "AME processor Usage". This will show the CPU overhead.

A maybe more important drawback of keeping AME enabled (even with a factor of 1) is that AIX will solely use 4K pages in that situation. So you don't have multiple page size support, even if AIX is configured for it.
0
 

Author Comment

by:aanya247
ID: 39938114
Ohhh I didnot know that, So first thing how do I check the page size as I know that we have large pages enabled on the server and also on the network.
0
 
LVL 68

Expert Comment

by:woolmilkporc
ID: 39938135
vmo  -a | grep lgpg

"lgpg_regions" specifies the number of large pages to reserve, and "lgpg_size" specifies the size in bytes of the hardware-supported large pages.

"vmstat -l" will show the number of large pages in use under "large-page". "alp" is "active large pages" and "flp" is "free large pages".

The network does not come into play here.
0

Featured Post

Live: Real-Time Solutions, Start Here

Receive instant 1:1 support from technology experts, using our real-time conversation and whiteboard interface. Your first 5 minutes are always free.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Suggested Solutions

Hello fellow BSD lovers, I've created a patch process for patching openjdk6 for BSD (FreeBSD specifically), although I tried to keep all BSD versions in mind when creating my patch. Welcome to OpenJDK6 on BSD First let me start with a little …
Installing FreeBSD… FreeBSD is a darling of an operating system. The stability and usability make it a clear choice for servers and desktops (for the cunning). Savvy?  The Ports collection makes available every popular FOSS application and packag…
Learn several ways to interact with files and get file information from the bash shell. ls lists the contents of a directory: Using the -a flag displays hidden files: Using the -l flag formats the output in a long list: The file command gives us mor…
In a previous video, we went over how to export a DynamoDB table into Amazon S3.  In this video, we show how to load the export from S3 into a DynamoDB table.

786 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question