Re: scalablility problem

Tom Lane wrote:
> "Joshua D. Drake"  writes:
>>> I use RHEL 4. I can not understand how the scalability related with 
>>> shared memory?
> 
>> It isn't RHEL4 and shared memory. It is PostgreSQL and shared memory. 
>> Things have changed with PostgreSQL since 7.3 (7.3 is really god awful 
>> old) that allow it to more effectively access shared memory and thus 
>> provide better performance.
> 
> Some specifics:
> 
> * bufmgr algorithms redesigned to allow larger number of shared buffers
> to be used effectively
> 
> * bufmgr redesigned to not have a single lock for management of all
> shared buffers; likewise for lockmgr
> 
> * lots of marginal tweaks such as paying attention to cache line
> alignment of "hot" shared data structures
> 
> I'm probably forgetting some things but I think the bufmgr and lockmgr
> changes were the biggest improvements in this area.
> 
> 			regards, tom lane
That is very helpful. Thanks!

Xiaoning
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