Обсуждение: utilising multi-cpu/core machines?
Hi I couldnt find any specifics on this subject in the documentation, so I thought I'd ask the group. how does pg utilise multi cpus/cores, i.e. does it use more than one core? and possibly, how, are there any documentation about this. thomas
On 9/5/07, Thomas Finneid <tfinneid@student.matnat.uio.no> wrote: > how does pg utilise multi cpus/cores, i.e. does it use more than one > core? and possibly, how, are there any documentation about this. Unlike other systems which manage their own affinity and prioritization, Postgres relies solely on the OS to handle process management across multiple CPUs/cores. -- Jonah H. Harris, Software Architect | phone: 732.331.1324 EnterpriseDB Corporation | fax: 732.331.1301 33 Wood Ave S, 3rd Floor | jharris@enterprisedb.com Iselin, New Jersey 08830 | http://www.enterprisedb.com/
On 9/5/07, Thomas Finneid <tfinneid@student.matnat.uio.no> wrote: > how does pg utilise multi cpus/cores, i.e. does it use more than one > core? and possibly, how, are there any documentation about this. PostgreSQL creates a new process to handle each connection to the database. Multiple sessions can therefore spread across multiple cores, but a single session will never use more than one.
>>> On Wed, Sep 5, 2007 at 5:41 PM, in message <46DF3082.7040301@ifi.uio.no>, Thomas Finneid <tfinneid@student.matnat.uio.no> wrote: > how does pg utilise multi cpus/cores, i.e. does it use more than one > core? and possibly, how, are there any documentation about this. For portability reasons PostgreSQL doesn't use threads, per se, but spawns a new process for each connection, and a few for other purposes. Each process may be running on a separate CPU, but a single connection will only be using one -- directly, anyway. (The OS may well be using the other for I/O, etc.) For documentation, you could start with this: http://www.postgresql.org/docs/8.2/interactive/app-postgres.html -Kevin
Hi Thomas, PostgreSQL does scale up very well. But you have to keep in mind that this also depends on profile of the application you're on PostgreSQL. Insufficient memory and slow disk systems can interfere PostgreSQL. Another issue is contention if the server has more than 4 cpus. (Please check out discussions about "context strom" in this group.) Anyhow, I had create a benchmark for my company which shows the scale up of PostgreSQL 8.1.4. This benchmark does try to enforce contention because of the profile of our application. Clients/scale-up factor 1 1 2 1,78 3 2,47 4 3,12 5 3,62 6 4,23 7 4,35 8 4,79 9 5,05 10 5,17 Scale-up factor is relative to one client the number of completed queries in a time frame. (throughput) This test was done on a 16 core Intel-box (4-way Xeon E7340). The results of TPC-B benchmark are looking similar. Sven. Thomas Finneid schrieb: > Hi > > I couldnt find any specifics on this subject in the documentation, so I > thought I'd ask the group. > > how does pg utilise multi cpus/cores, i.e. does it use more than one > core? and possibly, how, are there any documentation about this. > > thomas > > ---------------------------(end of broadcast)--------------------------- > TIP 6: explain analyze is your friend -- Sven Geisler <sgeisler@aeccom.com> Tel +49.30.921017.81 Fax .50 Senior Developer, AEC/communications GmbH & Co. KG Berlin, Germany