Re: postgresql and smp linux kernel
От | Scott Marlowe |
---|---|
Тема | Re: postgresql and smp linux kernel |
Дата | |
Msg-id | 1092056003.27166.309.camel@localhost.localdomain обсуждение исходный текст |
Ответ на | postgresql and smp linux kernel (zhicheng wang <wang_zc@yahoo.co.uk>) |
Список | pgsql-general |
On Mon, 2004-08-09 at 04:10, zhicheng wang wrote: > Dear all > > i have a dedicated server mainly running postgresql, > currently rh-posgtresql-7.3.6.7 (and samba, ypbind > etc). The server is a dual processor machine and the > OS is RHEL AS 3. > > I am currently running kernel-smp-2.4.21-15.0.4.EL. > > My question is: do i need to run smp kernel for > postgresql? What is benefit of it? If I run UP kernel, > what do I lose from the point view of PG? Let's be clear here, PostgreSQL isn't responsible for exploiting your second CPU, the OS is. The face that PostgreSQL spawns a new backend process for each connection means that it can use about as many processors as it has connections, plus maybe one for the OS. However, the OS will not schedule anything to run at all on the second CPU if you run a UP kernel. Generally, the linux and bsd kernels both tend to get a scaling factor of near unity for the second CPU with enough things to do in parallel. There's almost no loss for single processes hogging one CPU, and even these tasks are often sped up by the OS having a CPU to run on while your one big process is hogging the other one. Considering you're running samba, which is also process based, it would be wise to enable the second CPU in the kernel, otherwise pull it, put in the terminator, and save it in case of future CPU failure. It won't be doing you any good.
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