Re: "Priority Mechanisms for OLTP and Transactional Web Applications"
| От | Dann Corbit |
|---|---|
| Тема | Re: "Priority Mechanisms for OLTP and Transactional Web Applications" |
| Дата | |
| Msg-id | D425483C2C5C9F49B5B7A41F89441547055B49@postal.corporate.connx.com обсуждение исходный текст |
| Список | pgsql-hackers |
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. > > > > > > > > <html xmlns:o="urn:schemas-microsoft-com:office:office" > xmlns:w="urn:schemas-microsoft-com:office:word" > xmlns="http://www.w3.org/TR/REC-html40"> > > > > <head> > > <META HTTP-EQUIV="Content-Type" CONTENT="text/html; charset=us-ascii"> > > <meta name=Generator content="Microsoft Word 11 (filtered medium)"> > > <style> > > <!-- > > /* Style Definitions */ > > p.MsoNormal, li.MsoNormal, div.MsoNormal > > {margin:0in; > > margin-bottom:.0001pt; > > font-size:12.0pt; > > font-family:"Times New Roman";} > > a:link, span.MsoHyperlink > > {color:blue; > > text-decoration:underline;} > > a:visited, span.MsoHyperlinkFollowed > > {color:purple; > > text-decoration:underline;} > > span.EmailStyle17 > > {mso-style-type:personal-compose; > > font-family:Arial; > > color:windowtext;} > > @page Section1 > > {size:8.5in 11.0in; > > margin:1.0in 1.25in 1.0in 1.25in;} > > div.Section1 > > {page:Section1;} > > --> > > </style> > > > > </head> > > > > <body lang=EN-US link=blue vlink=purple> > > > > <div class=Section1> > > > > <p class=MsoNormal><font size=2 face=Arial><span style='font- > 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:p></o:p></span></font></p> > > > > <p class=MsoNormal><font size=2 face=Arial><span style='font- > size:10.0pt; > > font-family:Arial'><o:p> </o:p></span></font></p> > > > > <p class=MsoNormal><font size=2 face=Arial><span style='font- > 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:p></o:p></span></font></p> > > > > <p class=MsoNormal><font size=2 face=Arial><span style='font- > size:10.0pt; > > font-family:Arial'><o:p> </o:p></span></font></p> > > > > <p class=MsoNormal><font size=2 face=Arial><span style='font- > 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:p></o:p></span></font></p> > > > > <p class=MsoNormal><font size=2 face=Arial><span style='font- > size:10.0pt; > > font-family:Arial'><o:p> </o:p></span></font></p> > > > > <p class=MsoNormal><font size=2 face=Arial><span style='font- > 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:p></o:p></span></font></p> > > > > <p class=MsoNormal><font size=2 face=Arial><span style='font- > size:10.0pt; > > font-family:Arial'><o:p> </o:p></span></font></p> > > > > </div> > > > > </body> > > > > </html> > > -- > Hollywood is where if you don't have happiness you send out for it. > -- Rex Reed
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