I found said formula here: http://lists.mysql.com/maxdb/19208
"10.000 pages x 8 KB are about 80 MB and you need some shared areas for the libraries and for each connection. So 94 MB is exact the memory that's expected. "
This statement led me to believe "connection" = a user task.
"Each usertask needs _MAXTASK_STACK KB of memory.
The value for _MAXTASK_STACK depends on the operating system and the version used (you are using 7.3, aren't you?). It varies between 310 (7.3),
400 (7.4) and 1024 KB."
Could you direct me to where you found that information? (assuming it's not from your head?)
So MAXUSERTASKS * _MAXTASK_STACK KB + 64 KB = consumed memory. Is there a breakdown of a usertask, in terms of shared/virtual memory? Or rather, how much of a usertask is implemented in shared memory? And how much in the virtual memory?
As I understand it, local connections communicate through IPC/SHM --- so I'd imagine it varies, depending on how the connection originated?
Thanks for your patience,
JLS
Zabach, Elke wrote:
John L. Singleton wrote:
Hello Everyone,
I'm trying to come up with some sort of utilization formula for user tasks. I've seen at least three on this list---all of them different.
The ones I've seen:
MAXUSERTASKS *310KB + some other stuff
Each usertask needs _MAXTASK_STACK KB of memory.
The value for _MAXTASK_STACK depends on the operating system and the version used (you are using 7.3, aren't you?). It varies between 310 (7.3),
400 (7.4) and 1024 KB.
Additionally each usertask needs at least 64KB local cache.
MAXUSERTASKS * 10.000 pages * 8KB
where does this come from? Was it a discussion about the size of the data cache? I do not know such a value per user task. It may have been an advice for a data cache with enough space for several parallel users. But it depends on your database size, the table sizes usually used,..
Elke
SAP Labs Berlin
Does anyone have the goods on this parameter? I'm interested in determining two values:
1> The amount of shared memory required per user task. (ie, what to set SHMMAX, etc. to)
2> The amount of physical/virtual memory required, per user task.
Thanks! John L. Singleton
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