Re: "Priority Mechanisms for OLTP and Transactional Web Applications"

#1 (**permalink**) 04-11-2008, 04:44 AM

Yes. Something simple that can provide clear, tangible benefits is the
best kind of improvement.

I am sure that adding parameters to the command line of PostgreSQL which
enables superior tuning for differing computer systems would be wildly
appreciated.

> -----Original Message-----
> From: cache+@cs.cmu.edu [mailto:cache+@cs.cmu.edu]
> Sent: Wednesday, May 04, 2005 11:40 AM
> To: Dann Corbit
> Cc: harchol@cs.cmu.edu; natassa@cmu.edu; bianca@cs.cmu.edu;
> cache@cs.cmu.edu
> Subject: "Priority Mechanisms for OLTP and Transactional Web
Applications"
>
>
> In our experimentation, we simply used a user-defined function to
> handle changing the priority of transactions' threads. It shouldn't
> be hard to port the implementation back into postgres --- and
> provide an administrative mechanism to assign priorities. Do you
> think that PostgreSQL core would be interested in integrating
> priorities of service in this manner? I'd be very interested in
> helping out with this.
>
> -David
>
>
> Dann Corbit writes:
> > I have a question about your conclusion and the experiments as they
> > relate to the PostgreSQL database. In the paper, we find this:
> >
> >
> >
> > "For example, we find that for PostgreSQL running under TPC-C, the
> > simplest CPU scheduling algorithm CPU-Prio provides a factor of 2
> > improvement for the high-priority transactions, and adding priority
> > inheritance (CPU-Prio-Inherit) brings this up to a factor of near 6
> > improvement under high loads, while hardly penalizing low-priority
> > transactions. For PostgreSQL running under the TPC-W workload, we
find
> > that the best scheduling algorithm is the simplest CPU scheduling
> policy
> > CPU-Prio, which improves performance for high-priority transactions
by
> a
> > factor of up to 5. The reason why inheritance is more effective for
the
> > TPC-C example above is that TPC-C has much more data contention
than
> > TPC-W, leading to more priority inversions."
> >
> >
> >
> > To change the scheduling of the threads, did you modify the source
code
> > of the PostgreSQL database? If so, are the modifications
available?
> >
> >
> >
> > It seems that you have achieved a very significant performance
boost by
> > a priority change, and I would be interested to know if the
> > modifications are available and also if they can be plowed back
into
> the
> > PostgreSQL core.
> >
> >
> >
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> > size:10.0pt;
> > font-family:Arial'>I have a question about your conclusion and the
> experiments
> > as they relate to the PostgreSQL database.  In the paper, we
find
> this:<o

></o

>
> >
> > size:10.0pt;
> > font-family:Arial'><o

> </o

>
> >
> > size:10.0pt;
> > font-family:Arial'>"For example, we find that for PostgreSQL
> running under
> > TPC-C, the simplest CPU scheduling algorithm CPU-Prio provides a
factor
> of 2
> > improvement for the high-priority transactions, and adding priority
> inheritance
> > (CPU-Prio-Inherit) brings this up to a factor of near 6 improvement
> under high
> > loads, while hardly penalizing low-priority transactions.  For
> PostgreSQL
> > running under the TPC-W workload, we find that the best scheduling
> algorithm is
> > the simplest CPU scheduling policy CPU-Prio, which improves
performance
> for
> > high-priority transactions by a factor of up to 5. The reason why
> inheritance
> > is more effective for the TPC-C example above is that TPC-C has
much
> more data
> > contention than TPC-W, leading to more priority
> inversions."<o

></o

>
> >
> > size:10.0pt;
> > font-family:Arial'><o

> </o

>
> >
> > size:10.0pt;
> > font-family:Arial'>To change the scheduling of the threads, did you
> modify the
> > source code of the PostgreSQL database?  If so, are the
> modifications
> > available?<o

></o

>
> >
> > size:10.0pt;
> > font-family:Arial'><o

> </o

>
> >
> > size:10.0pt;
> > font-family:Arial'>It seems that you have achieved a very
significant
> > performance boost by a priority change, and I would be interested
to
> know if
> > the modifications are available and also if they can be plowed back
> into the
> > PostgreSQL core.<o

></o

>
> >
> > size:10.0pt;
> > font-family:Arial'><o

> </o

>
> >
> > </div>
> >
> > </body>
> >
> > </html>
>
> --
> Hollywood is where if you don't have happiness you send out for it.
> -- Rex Reed

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