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From:Devananda Date:August 25 2004 5:29pm
Subject:[Fwd: question about innodb_thread_concurrency]
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Hi,

This question is off topic of this list, about optimization of mysql's 
InnoDB performance, but I am asking it here since the 'general' list is 
overcrowded with questions pertaining to query syntax, etc,  ... I hope 
this is ok.



quoting the doc's..

> "The default value is 8. If you have low performance and |SHOW INNODB 
 > STATUS| reveals many threads waiting for semaphores,
> you may have thread thrashing and should try setting this parameter 
 > lower or higher..... A recommended value is the sum of the number of
 > processors and disks your system has. A value of 500 or greater
 > disables the concurrency checking."

What, then,  is a reasonable value for a dual Xeon 2.8Ghz with 6 disks? 
we are currently running with innodb_thread_concurrency=16. Each DB has 
200-400 active php clients, but there is a very common query which must 
return a large amount of data, and there appears to be quite a large 
backup within innodb. I have made sure it is not a bottleneck with the 
disks or cpu, and 'show innodb status' shows that there are the max 
number of queries inside innodb (15) and there are indeed a handfull of 
queries inside the queu at any given moment.

Any suggestions? Or experience with setting this option to 500?

Thanks :)

Devananda
Neopets, Inc



P.S. Perhaps there could be a list for 'high performace' mysql?


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[Fwd: question about innodb_thread_concurrency]Devananda25 Aug