Re: [PERFORM] Limited performance on multi core server

Matthew Lunnon wrote: Hi Sven, Does this mean that one option I have is to use a multi core Intel based server instead of an AMD based server? Wow... hold on. I remember that I also an issue with AMD Opterons before Pg 8.1 There is a specific Opteron behaviour on shared memory locks which a

Re: [PERFORM] Limited performance on multi core server

Matthew Lunnon wrote: Ah I was afraid of that. Maybe I'll have to come out of the dark ages. Yes :) but ignore the comment about the 8.3 Beta series. It is Beta for a reason, that means testing only, no production. Sincerely, Joshua D. Drake Your bottleneck is that you are using a very o

Re: [PERFORM] URI to kind of a benchmark

Harald Armin Massa wrote: reading postgres benchmarks for beginners advises to stop reading on the words "default (ie. unchanged postgresql.conf); but the real test is given right after: http://www.kaltenbrunner.cc/blog/index.php?/archives/21-guid.html That confirmes my first impression (on d

Re: [PERFORM] Limited performance on multi core server

Hi Matthew, You should be upgrade to Pg 8.2.5. We did test on different hardware. The bigest step is to use Pg 8.2.5. The high number of context switches which we saw before simple disappeared. In regards to you question about XEONs: You will have the similar issue with a XEON box. We tried diff

Re: [PERFORM] Limited performance on multi core server

Hi Sven, Does this mean that one option I have is to use a multi core Intel based server instead of an AMD based server? Matthew Sven Geisler wrote: Hi Matthew, I remember that I also an issue with AMD Opterons before Pg 8.1 There is a specific Opteron behaviour on shared memory locks which

[PERFORM] URI to kind of a benchmark

reading postgres benchmarks for beginners advises to stop reading on the words "default (ie. unchanged postgresql.conf); but the real test is given right after: http://www.kaltenbrunner.cc/blog/index.php?/archives/21-guid.html That confirmes my first impression (on different workload) of "the spe

Re: [PERFORM] Limited performance on multi core server

Hi Matthew, The apache is able to queue 1024 request. Reducing the number of max_clients was the key to deal with the problem of to much concurrent queries. We have monitored less concurrent http request after we decrease max_clients. We also have introduce a global statement timeout to stop long

Re: [PERFORM] Limited performance on multi core server

Hi Matthew, Please not that is no official patch, but it works with our Opteron server without any problems. You should run the regression test after you adapt it for Pg 7.4. Sven. Matthew Lunnon schrieb: > Hi Sven, > > yes the patch would be great if you could send it to me, we have already >

Re: [PERFORM] Limited performance on multi core server

Hi Sven, Yes I have done a reasonable amount of query tuning. The application is a web service using an apache/resin combination at the front end, we have thought about using resin threads to limit the number of connections but are worried about backing up connections in apache and getting s

Re: [PERFORM] Limited performance on multi core server

Hi Sven, yes the patch would be great if you could send it to me, we have already had to compile postgres to up the number of function parameters from 32 to 64. Meanwhile I will try and persuade my colleagues to consider the upgrade option. Thanks Matthew Sven Geisler wrote: Hi Matthew,

Re: [PERFORM] Limited performance on multi core server

Hi Matthew, I remember that I also an issue with AMD Opterons before Pg 8.1 There is a specific Opteron behaviour on shared memory locks which adds a extra "penalty" during the execution time for Pg code before 8.1. I can you provide my patch for Pg 8.0 which should be adaptable for Pg 7.4 if you

Re: [PERFORM] Limited performance on multi core server

Hi Matthew, The context switching isn't the issue. This is an indicator which is useful to identify your problem. What kind of application do you running? Can you limit the database clients? We have a web application based on apache running. We have a limit number of apache processes which are a

Re: [PERFORM] Limited performance on multi core server

On Wed, 12 Dec 2007, Matthew Lunnon wrote: I have a 4 * dual core 64bit AMD OPTERON server with 16G of RAM, running postgres 7.4.3. shared_buffers = 96000 As you've already been told repeatedly 7.4 is a release from long before optimizations to work well on a multi-core server like this. I'

Re: [PERFORM] Limited performance on multi core server

> Thanks for the information Claus, Why would reducing the effective cache > size help the processor usage? It seems that there is plenty of resources > on the box although I can see that 10MB of sort space could mount up if we > had 500 connections but at the moment we do not have anything like

Re: [PERFORM] Limited performance on multi core server

Thanks for the information Claus, Why would reducing the effective cache size help the processor usage? It seems that there is plenty of resources on the box although I can see that 10MB of sort space could mount up if we had 500 connections but at the moment we do not have anything like that

Re: [PERFORM] Limited performance on multi core server

Ah I was afraid of that. Maybe I'll have to come out of the dark ages. Matthew Steinar H. Gunderson wrote: On Wed, Dec 12, 2007 at 10:16:43AM +, Matthew Lunnon wrote: Does anyone have any ideas what my bottle neck might be and what I can do about it? Your bottleneck is that you

Re: [PERFORM] Limited performance on multi core server

Limiting the queries was our initial thought but we then hit a problem with connection pooling which didn't implement a fifo algorithm. Looks like I'll have to look deeper into the connection pooling. So you think the problem might be context switching on the server, I'll take a closer look a

Re: [PERFORM] Limited performance on multi core server

Hi Matthew, I know exactly what you experience. We had a 4-way DC Opteron and Pg 7.4 too. You should monitor context switches. First suggest upgrade to 8.2.5 because the scale up is much better with 8.2. You need to limit the number of concurrent queries to less than 8 (8 cores) if you need to

Re: [PERFORM] Limited performance on multi core server

> > Does anyone have any ideas what my bottle neck might be and what I can do > > about it? > > Your bottleneck is that you are using a very old version of PostgreSQL. Try > 8.2 or (if you can) the 8.3 beta series -- it scales a _lot_ better in this > kind of situation. You won't know until you've

Re: [PERFORM] Limited performance on multi core server

> I have a 4 * dual core 64bit AMD OPTERON server with 16G of RAM, running > postgres 7.4.3. This has been recompiled on the server for 64 stored > procedure parameters, (I assume this makes postgres 64 bit but are not > sure). When the server gets under load from database connections > executing

Re: [PERFORM] Limited performance on multi core server

On Wed, Dec 12, 2007 at 10:16:43AM +, Matthew Lunnon wrote: > Does anyone have any ideas what my bottle neck might be and what I can do > about it? Your bottleneck is that you are using a very old version of PostgreSQL. Try 8.2 or (if you can) the 8.3 beta series -- it scales a _lot_ better i

[PERFORM] Limited performance on multi core server

Hi, I have a 4 * dual core 64bit AMD OPTERON server with 16G of RAM, running postgres 7.4.3. This has been recompiled on the server for 64 stored procedure parameters, (I assume this makes postgres 64 bit but are not sure). When the server gets under load from database connections executing