- Community Home
- >
- Servers and Operating Systems
- >
- Legacy
- >
- Operating System - Tru64 Unix
- >
- Re: Shared memory allocation
Categories
Company
Local Language
Forums
Discussions
Forums
- Data Protection and Retention
- Entry Storage Systems
- Legacy
- Midrange and Enterprise Storage
- Storage Networking
- HPE Nimble Storage
Discussions
Discussions
Discussions
Forums
Forums
Discussions
Discussion Boards
Discussion Boards
Discussion Boards
Discussion Boards
- BladeSystem Infrastructure and Application Solutions
- Appliance Servers
- Alpha Servers
- BackOffice Products
- Internet Products
- HPE 9000 and HPE e3000 Servers
- Networking
- Netservers
- Secure OS Software for Linux
- Server Management (Insight Manager 7)
- Windows Server 2003
- Operating System - Tru64 Unix
- ProLiant Deployment and Provisioning
- Linux-Based Community / Regional
- Microsoft System Center Integration
Discussion Boards
Discussion Boards
Discussion Boards
Discussion Boards
Discussion Boards
Discussion Boards
Discussion Boards
Discussion Boards
Discussion Boards
Discussion Boards
Discussion Boards
Discussion Boards
Discussion Boards
Discussion Boards
Discussion Boards
Discussion Boards
Discussion Boards
Discussion Boards
Discussion Boards
Discussion Boards
Discussion Boards
Discussion Boards
Community
Resources
Forums
Blogs
- Subscribe to RSS Feed
- Mark Topic as New
- Mark Topic as Read
- Float this Topic for Current User
- Bookmark
- Subscribe
- Printer Friendly Page
- Mark as New
- Bookmark
- Subscribe
- Mute
- Subscribe to RSS Feed
- Permalink
- Report Inappropriate Content
тАО01-06-2006 03:42 AM
тАО01-06-2006 03:42 AM
Shared memory allocation
Any thoughts or better yet hands-on experience with this will be much appreciated!
- Mark as New
- Bookmark
- Subscribe
- Mute
- Subscribe to RSS Feed
- Permalink
- Report Inappropriate Content
тАО01-06-2006 05:38 AM
тАО01-06-2006 05:38 AM
Re: Shared memory allocation
- Mark as New
- Bookmark
- Subscribe
- Mute
- Subscribe to RSS Feed
- Permalink
- Report Inappropriate Content
тАО01-06-2006 02:48 PM
тАО01-06-2006 02:48 PM
Re: Shared memory allocation
The RAD-ness of GH memory allocaiton was IMHO secondary to the bigpage 4MB translation buffer page size. I also always thought GH was also a clear mechanisme to set aside memory for a specific (buffer cache) purpose, but it was infexible at that.
With bigpages you get the 4MB granularity, with flexibility, and applicable for data as well as code hopefully reducing DTB misses as well as ITB misses.
If you have a single big database, with all processes toucing all data , there is little you can do with NUMA locality anyway, and as indicated teh relative latencies on teh GS1280 really do not make it critical to think about it.
The only time I would consider exploiting numa tools like RUNON -R for the gs1280 is when the application has multiple distinct big process groups. Maybe a production database as well as a development and training database. For such circumstances I would consider running one group on a selected set of adjacent rads, and the other application(s) on the remaining RAD reducing the average memory latency for both.
For example, for a 16 p GS1280 the RADs might be labeled as:
00 01 02 03
04 05 06 07
08 09 10 11
12 13 14 15
The latencies from cell 0 could be roughly:
082 141 177 149
133 169 216 176
176 215 250 216
150 184 228 192
So if you pick 00,01,02,03,04,05, 07,08,12,13,15 for one set of apps, and give 06,09,10,11,14 to the an other set of apps, then the large set will never need a 5 hop path, and the small set only 2 hops at the most.
[Ok, I have not calculated all the path's, but something along those lines no?]
fwiw,
Hein.
- Mark as New
- Bookmark
- Subscribe
- Mute
- Subscribe to RSS Feed
- Permalink
- Report Inappropriate Content
тАО01-07-2006 01:48 AM
тАО01-07-2006 01:48 AM
Re: Shared memory allocation
Ok, hop-counts are of course 0 based. What I called 5 hops was just 4, but still.
I happened to stumble into the 2002 Numa paper.
It is good to re-read that:
It uses the same numbering, but the picture is much nicer tha the cryptic matrix I provided.
http://h30097.www3.hp.com/docs/base_doc/DOCUMENTATION/V51_HTML/NUMA/TITLE.HTM
btw.. they also made a counting error/oversight:
" Three hops away if the resources are in RADs 5, 10, and 13"
... RAD 14 is also 3 hops, and RAD 12 4 hops
In the kernel there is a hop-count table, I believe from every rad to any other rad to help the scheduler algoritme (leash).
hth,
Hein.
- Mark as New
- Bookmark
- Subscribe
- Mute
- Subscribe to RSS Feed
- Permalink
- Report Inappropriate Content
тАО01-09-2006 02:20 AM
тАО01-09-2006 02:20 AM
Re: Shared memory allocation
If the vendor won't go along with big pages, would it be reasonable to fall back to the (admittedly less flexible) rad_gh_regions approach?
- Mark as New
- Bookmark
- Subscribe
- Mute
- Subscribe to RSS Feed
- Permalink
- Report Inappropriate Content
тАО01-10-2006 12:10 AM
тАО01-10-2006 12:10 AM
Re: Shared memory allocation
Yes, GH is desriable if big-pages can not be use.
There are several other topics in this forum with discussions in this area:
http://forums1.itrc.hp.com/service/forums/questionanswer.do?threadId=846477
- Be sure to set a high minimal threshold to avoid inintended shmget calls to allocate from it
- Be sure to make gh allocation failures none fatal in case the need changes (in a few years) when you are not around/able to adjust the current size.
- Check the usage with cda/crash, or my tool as descibed in topic:
http://forums1.itrc.hp.com/service/forums/questionanswer.do?threadId=644238
hth,
Hein.
- Mark as New
- Bookmark
- Subscribe
- Mute
- Subscribe to RSS Feed
- Permalink
- Report Inappropriate Content
тАО01-10-2006 12:13 AM
тАО01-10-2006 12:13 AM
Re: Shared memory allocation
That said, I submit that little investment in AlphaServer benchmarking has likely occurred at XXXX for some time. So there may be something here that is usefull, but no other XXXX customer uses.
I believe that by default, that shared memory will be distributed across the RAD's in default mode, but I can't remember for sure.
As you ramp up during testing and golive keep an eye on your QBB memory usage, using collect -s m. Sometimes you'll see one QBB (that is next to an IO hose or something) getting quickly consumed (~0 free) while others do not. If you do, approach HP for solutions.
- Mark as New
- Bookmark
- Subscribe
- Mute
- Subscribe to RSS Feed
- Permalink
- Report Inappropriate Content
тАО01-10-2006 01:48 AM
тАО01-10-2006 01:48 AM
Re: Shared memory allocation
Adam, I think you might be getting the GS1280 (Marvel) machines mixed up with the prior class of machines. The GS1280 does away with the concept of the QBB entirely. And good luck in your post-XXXX endeavors ;-)
- Mark as New
- Bookmark
- Subscribe
- Mute
- Subscribe to RSS Feed
- Permalink
- Report Inappropriate Content
тАО01-11-2006 01:13 AM
тАО01-11-2006 01:13 AM