Re: Low Performance for big hospital server ..

Dave Cramer wrote:

> 
> 
> William Yu wrote:
> 
>> amrit@health2.moph.go.th wrote:
>>
>>> I will try to reduce shared buffer to 1536 [1.87 Mb].
>>
>>
>>
>> 1536 is probaby too low. I've tested a bunch of different settings on 
>> my  8GB Opteron server and 10K seems to be the best setting.
> 
> 
> Be careful here, he is not using opterons which can access physical 
> memory above 4G efficiently. Also he only has 4G the 6-10% rule still 
> applies

10% of 4GB is 400MB. 10K buffers is 80MB. Easily less than the 6-10% rule.


>> To figure out your effective cache size, run top and add free+cached.
> 
> 
> My understanding is that effective cache is the sum of shared buffers, 
> plus kernel buffers, not sure what free + cached gives you?

Not true. Effective cache size is the free memory available that the OS 
can use for caching for Postgres. In a system that runs nothing but 
Postgres, it's free + cached.