From: | Dave Cramer <pg(at)fastcrypt(dot)com> |
---|---|
To: | Bill Montgomery <billm(at)lulu(dot)com> |
Cc: | Michael Adler <adler(at)pobox(dot)com>, perform <pgsql-performance(at)postgresql(dot)org> |
Subject: | Re: Excessive context switching on SMP Xeons |
Date: | 2004-10-14 19:59:14 |
Message-ID: | 1097783954.7978.501.camel@localhost.localdomain |
Views: | Raw Message | Whole Thread | Download mbox | Resend email |
Thread: | |
Lists: | pgsql-performance |
Bill,
In order to manifest the context switch problem you will definitely
require clients to be set to more than one in pgbench. It only occurs
when 2 or more backends need access to shared memory.
If you want help backpatching Gavin's patch I'll be glad to do it for
you, but you do need a recent kernel.
Dave
On Thu, 2004-10-07 at 14:48, Bill Montgomery wrote:
> Michael Adler wrote:
>
> >On Thu, Oct 07, 2004 at 11:48:41AM -0400, Bill Montgomery wrote:
> >
> >
> >>Alan Stange wrote:
> >>
> >>The same test on a Dell PowerEdge 1750, Dual Xeon 3.2 GHz, 512k cache,
> >>HT on, Linux 2.4.21-20.ELsmp (RHEL 3), 4GB memory, pg 7.4.5:
> >>
> >>Far less performance that the Dual Opterons with a low number of
> >>clients, but the gap narrows as the number of clients goes up. Anyone
> >>smarter than me care to explain?
> >>
> >>
> >
> >You'll have to wait for someone smarter than you, but I will posit
> >this: Did you use a tmpfs filesystem like Alan? You didn't mention
> >either way. Alan did that as an attempt remove IO as a variable.
> >
> >-Mike
> >
> >
>
> Yes, I should have been more explicit. My goal was to replicate his
> experiment as closely as possible in my environment, so I did run my
> postgres data directory on a tmpfs.
>
> -Bill Montgomery
>
> ---------------------------(end of broadcast)---------------------------
> TIP 4: Don't 'kill -9' the postmaster
--
Dave Cramer
519 939 0336
ICQ # 14675561
www.postgresintl.com
From | Date | Subject | |
---|---|---|---|
Next Message | Kevin Brown | 2004-10-14 20:25:31 | Re: First set of OSDL Shared Mem scalability results, some wierdness ... |
Previous Message | Reini Urban | 2004-10-14 19:40:59 | Re: Performance on Win32 vs Cygwin |