RE: [SLE] P4 Hyperthreading in BIOS: Enable or disable?
-----Original Message----- From: Michael W Cocke [mailto:cocke@catherders.com] Sent: Thursday, January 12, 2006 10:36 AM To: suse-linux-e@suse.com Subject: Re: [SLE] P4 Hyperthreading in BIOS: Enable or disable?
On Thu, 12 Jan 2006 10:33:15 -0500, you wrote:
Jon Nelson wrote:
On Wed, 11 Jan 2006, Randall R Schulz wrote:
Jon,
On Wednesday 11 January 2006 09:43, Jon Nelson wrote:
...
So, is it necessary to enable hyperthreading in BIOS, or does Linux just ignore that setting and utilizes the CPU's full capabilities anyhow? Yes, enable it if you want to take advantage of it. However, of late there have been some interesting articles that suggest that turning hyperthreading *off* may be faster than having it on. Care to share?
I suspect you can use google just as easily as I. I'm sorry, I don't have the articles on hand or bookmarked or whatever - why bother when google is better?
http://news.zdnet.co.uk/0,39020330,39237341,00.htm which is linked to from http://hardware.slashdot.org/article.pl?sid=05/11/19/1358218&tid=118&tid =126&tid=137
Marlier, Ian wrote:
Yes, enable it if you want to take advantage of it. However, of late there have been some interesting articles that suggest that turning hyperthreading *off* may be faster than having it on.
http://news.zdnet.co.uk/0,39020330,39237341,00.htm
which is linked to from
http://hardware.slashdot.org/article.pl?sid=05/11/19/1358218
Thanks for adding the /. link as well. It has some good comments (if you read at +4, like I do.) Seems like HT is bad for I/O-dominant workloads that don't take HT into account, and good for workloads with many applications running at the same time that don't thrash the L2 cache. Joachim -- =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- Joachim Schrod Email: jschrod@acm.org Roedermark, Germany
HT is very useful and delivers considerable advantages for compiling and
development workstations. Just be aware that although Linux sees 2
processors, in real terms HT is only equal to about 1.5 processors so set
any application/server configs based on the number of CPU's accordingly.
You can otherwise run into loading issues and temperature problems with the
CPU.
On 1/13/06, Joachim Schrod
Marlier, Ian wrote:
> Yes, enable it if you want to take advantage of it. > However, of late there have been some interesting articles that > suggest that turning hyperthreading *off* may be faster than having > it on.
http://news.zdnet.co.uk/0,39020330,39237341,00.htm
which is linked to from
http://hardware.slashdot.org/article.pl?sid=05/11/19/1358218
Thanks for adding the /. link as well. It has some good comments (if you read at +4, like I do.)
Seems like HT is bad for I/O-dominant workloads that don't take HT into account, and good for workloads with many applications running at the same time that don't thrash the L2 cache.
Joachim
-- =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- Joachim Schrod Email: jschrod@acm.org Roedermark, Germany
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participants (3)
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Joachim Schrod -
Mark Keir -
Marlier, Ian