From: Xiaoning Ding <dingxn@cse.ohio-state.edu>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Joshua D. Drake <jd@commandprompt.com>
Cc: Scott Marlowe <smarlowe@g2switchworks.com>
Cc: pgsql-performance@postgresql.org
Subject: Re: scalablility problem
Date: Sat, 31 Mar 2007 13:08:25 -0400
Message-ID: <460E9589.6070103@cse.ohio-state.edu> (raw)
In-Reply-To: <6434.1175358708@sss.pgh.pa.us>
References: <460D7220.9010302@cse.ohio-state.edu>
<1175290903.25022.110.camel@state.g2switchworks.com>
<460E8198.1010604@cse.ohio-state.edu>
<460E82ED.8070106@commandprompt.com>
<6434.1175358708@sss.pgh.pa.us>
Tom Lane wrote:
> "Joshua D. Drake" <jd@commandprompt.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
>
>
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To: pgsql-performance@postgresql.org
Cc: dingxn@cse.ohio-state.edu, tgl@sss.pgh.pa.us, jd@commandprompt.com, smarlowe@g2switchworks.com
Subject: Re: scalablility problem
In-Reply-To: <460E9589.6070103@cse.ohio-state.edu>
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