| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | "Joshua D(dot) Drake" <jd(at)commandprompt(dot)com> |
| Cc: | Xiaoning Ding <dingxn(at)cse(dot)ohio-state(dot)edu>, Scott Marlowe <smarlowe(at)g2switchworks(dot)com>, pgsql-performance(at)postgresql(dot)org |
| Subject: | Re: scalablility problem |
| Date: | 2007-03-31 16:31:48 |
| Message-ID: | 6434.1175358708@sss.pgh.pa.us |
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| Lists: | pgsql-performance |
"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
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