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Re: smp , php and postmaster distant

From: Chris Albertson <calbertson(at)logicon(dot)com>
To: Dana Hudes <dhudes(at)hudes(dot)org>
Cc: Loïc TREGOUËT <loic(at)ext(dot)cri74(dot)org>, pgsql-admin(at)postgresql(dot)org
Subject: Re: smp , php and postmaster distant
Date: 2000-06-22 18:28:28
Message-ID: (view raw, whole thread or download thread mbox)
Lists: pgsql-admin
Dana Hudes wrote:
> Your gain from SMP under such situation is the application has a cpu for itself
> and all the system overhead processes run on the other cpu.

The above is correct, but Postgresql uses one process per connection.
This is a (possibly crude) from for multi threading.  But it is the same
way the web server works.  The process is forked.  In the systems I've seen
it is common to have four to eight simultaneous open connections to
the database.  Multiple CPUs _do_ help in this case.

The question below is hard to answer.  If I read it correctly he is asking
"Why is performance go down when I switched to a dual CPU system?"  He does
not provide detailed information about the configuration of his system both
before and after the change so we can't answer.  Perhaps he had fsync disabled
then but no now.  Who knows?  A lot more detail is required.

My point is one more that with Postgresql, multiple CPUs can help if you have
multiple active clients.

> > Hie ,
> >
> >
> >     I have put a database on a 2 processors db server . (2 * PII 450 Mhz
> > with 512 Mo RAM)
> >
> >     This server is distant from the web server .
> >
> >     I've a php3 interface and , i've seen some big loose of performance
> > .
> >
> >     The request are longer when i use the bi-processor .
> >
> >     Is it due to the distant server or do i need some configurations to
> > postmaster to accept multi prcocessors ?
> >
> >     The web server and the database server are link with a 100Mbit link
> > !
> >
> >                                                             thanks for
> > all

  Chris Albertson

  calbertson(at)logicon(dot)com                  Voice: 626-351-0089  x17
  Logicon, Pasadena California            Fax:   626-351-0699

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