Re: scalablility problem

[Xiaoning Ding <dingxn(at)cse(dot)ohio-state(dot)edu>]

Tom Lane wrote:
> "Joshua D. Drake" <jd(at)commandprompt(dot)com> 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
>