Re: Linux vs. Windows performance.

Michael Rothwell <marothwellRemoveThis_at_yahoo.com> wrote in message news:<ltidnQqeOq0ewK_dRVn-hA_at_comcast.com>...
> NorwoodThree wrote:
> > Something else to consider-
> >
> > On the Linux side, I know that if you use Dell equipment and a Pentium
> > 4 processor, you can enable hyper-threading for the processor in the
> > BIOS. This essentially gives you 2 processors in one. It basically
> > is a virtual 2 processor configuration.
> >
> > Not sure if Windows takes advantages of the HyperThreading, but Linux
> > and Oracle do. And it is fully supported.
>
> Thanks, this is the kind of information that I was looking for. We have
> an instance that we are considering moving the OS to linux, and just
> wanted some idea of what to expect with performance.
>
> Michael

last time I checked, the 2.4 kernel did not differentiate between physical and logical CPUs. That functionality was in 2.5 (dev) and would be in 2.6.

someone may have backported that functionality into a 2.4 kernel.

In any event, disabling Hyperthreading is always an option, but a reboot is required. Testing would be best.

I believe that OSDL (open source development labs) did some testing of Hyperthreading.
check:
http://www.osdl.org/cgi-bin/eidetic.cgi?command=display&modulename=projects&on=1149 "Identify Hyper-threading performance improvements in Linux 2.4 and 2.5"

and this is worth a read:
http://www-124.ibm.com/developerworks/oss/linuxperf/

a quick search of the web returned this off of the Debian mailing list http://lists.debian.org/debian-user/2003/debian-user-200301/msg00720.html

So - if you are still running a 2.4.x kernel, I'd disable it if you have more than 1 physical CPU. When you are ready to install a 2.6.x kernel, re-enable it.

Oracle was very non-specific regarding hypterthreading and per-CPU licensing, so I had disabled it for servers that had Oracle software installed. A month or so back, we received word that the per-CPU licensing was per physical processor, not virtual processor, and that hypterthreading _could_ be enabled.

as always, check with your Oracle Salesperson.

Pd Received on Tue Feb 17 2004 - 17:52:16 CST