P4 Hyperthreading in BIOS: Enable or disable?
Hello, I have a system with a Pentium P4 and an Intel D865GBF mainboard. The CPU has hyperthreading, but this is disabled in the BIOS. (The system got delivered that way. I bought it w/o any operating system.) Nevertheless, SUSE 10.0 seems to detect Hyperthreading, since it uses an SMP kernel. Also, /proc/cpuinfo contains the lines model name : Intel(R) Pentium(R) 4 CPU 3.00GHz stepping : 1 cpu MHz : 2993.250 cache size : 1024 KB physical id : 0 siblings : 2 core id : 0 cpu cores : 1 where -- as far as I understood -- a `siblings' line with a value >1 denotes hyperthreading. So, is it necessary to enable hyperthreading in BIOS, or does Linux just ignore that setting and utilizes the CPU's full capabilities anyhow? TIA for any answer, Joachim -- =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- Joachim Schrod Email: jschrod@acm.org Roedermark, Germany
On Wed, 11 Jan 2006, Joachim Schrod wrote:
Hello,
I have a system with a Pentium P4 and an Intel D865GBF mainboard. The CPU has hyperthreading, but this is disabled in the BIOS. (The system got delivered that way. I bought it w/o any operating system.)
Nevertheless, SUSE 10.0 seems to detect Hyperthreading, since it uses an SMP kernel. Also, /proc/cpuinfo contains the lines
model name : Intel(R) Pentium(R) 4 CPU 3.00GHz stepping : 1 cpu MHz : 2993.250 cache size : 1024 KB physical id : 0 siblings : 2 core id : 0 cpu cores : 1
where -- as far as I understood -- a `siblings' line with a value >1 denotes hyperthreading.
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.
--
Carpe diem - Seize the day.
Carp in denim - There's a fish in my pants!
Jon Nelson
On 1/11/06, Jon Nelson
On Wed, 11 Jan 2006, Joachim Schrod wrote:
Hello,
I have a system with a Pentium P4 and an Intel D865GBF mainboard. The CPU has hyperthreading, but this is disabled in the BIOS. (The system got delivered that way. I bought it w/o any operating system.)
Nevertheless, SUSE 10.0 seems to detect Hyperthreading, since it uses an SMP kernel. Also, /proc/cpuinfo contains the lines
model name : Intel(R) Pentium(R) 4 CPU 3.00GHz stepping : 1 cpu MHz : 2993.250 cache size : 1024 KB physical id : 0 siblings : 2 core id : 0 cpu cores : 1
where -- as far as I understood -- a `siblings' line with a value >1 denotes hyperthreading.
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.
Interestingly, most articles are controversial, some of them
suggesting turning it off others claim to have achieved performance
improvements of more than 30%.
Besides this, Intels HT-enabled processors suffer from a security
design flaw allowing unprivileged users to steal an RSA private key
being used on the same machine as an exploit showed at BSDCan05. Read
more about it in http://www.daemonology.net/papers/htt.pdf.
\Steve
--
Steve Graegert
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?
... Jon Nelson
Randall Schulz
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?
--
Carpe diem - Seize the day.
Carp in denim - There's a fish in my pants!
Jon Nelson
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?
-- Carpe diem - Seize the day. Carp in denim - There's a fish in my pants!
Jon Nelson
I believe he is asking you to back up your statement with fact since you mentioned it. LDB
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?
-- Carpe diem - Seize the day. Carp in denim - There's a fish in my pants!
Jon Nelson
I believe he is asking you to back up your statement with fact since you mentioned it.
LDB
I read the same article - I seem to recall it was on /. google would probably be a good way to find it. Mike- -- If you're not confused, you're not trying hard enough. -- Please note - Due to the intense volume of spam, we have installed site-wide spam filters at catherders.com. If email from you bounces, try non-HTML, non-encoded, non-attachments,
On Wednesday 11 January 2006 12:25, Joachim Schrod wrote:
Hello,
I have a system with a Pentium P4 and an Intel D865GBF mainboard. The CPU has hyperthreading, but this is disabled in the BIOS. (The system got delivered that way. I bought it w/o any operating system.)
Nevertheless, SUSE 10.0 seems to detect Hyperthreading, since it uses an SMP kernel. Also, /proc/cpuinfo contains the lines
model name : Intel(R) Pentium(R) 4 CPU 3.00GHz stepping : 1 cpu MHz : 2993.250 cache size : 1024 KB physical id : 0 siblings : 2 core id : 0 cpu cores :
I don't think it's working for you. You should see two processors listed. Here's mine: cat cpuinfo processor : 0 vendor_id : GenuineIntel cpu family : 15 model : 2 model name : Intel(R) Pentium(R) 4 CPU 2.80GHz stepping : 9 cpu MHz : 2800.390 cache size : 512 KB physical id : 0 siblings : 2 core id : 0 cpu cores : 1 fdiv_bug : no hlt_bug : no f00f_bug : no coma_bug : no fpu : yes fpu_exception : yes cpuid level : 2 wp : yes flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe cid xtpr bogomips : 5614.93 processor : 1 vendor_id : GenuineIntel cpu family : 15 model : 2 model name : Intel(R) Pentium(R) 4 CPU 2.80GHz stepping : 9 cpu MHz : 2800.390 cache size : 512 KB physical id : 0 siblings : 2 core id : 0 cpu cores : 1 fdiv_bug : no hlt_bug : no f00f_bug : no coma_bug : no fpu : yes fpu_exception : yes cpuid level : 2 wp : yes flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe cid xtpr bogomips : 5589.26 You would also need dual channel memory. Try enabling it in the bios and see what happens. If you can't enable it, then your hw probably isn't capable of it.
1
where -- as far as I understood -- a `siblings' line with a value >1 denotes hyperthreading.
So, is it necessary to enable hyperthreading in BIOS, or does Linux just ignore that setting and utilizes the CPU's full capabilities anyhow?
TIA for any answer,
Joachim
-- =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- Joachim Schrod Email: jschrod@acm.org Roedermark, Germany
Joachim Schrod wrote:
Hello,
I have a system with a Pentium P4 and an Intel D865GBF mainboard. The CPU has hyperthreading, but this is disabled in the BIOS. (The system got delivered that way. I bought it w/o any operating system.)
Nevertheless, SUSE 10.0 seems to detect Hyperthreading, since it uses an SMP kernel. Also, /proc/cpuinfo contains the lines
model name : Intel(R) Pentium(R) 4 CPU 3.00GHz stepping : 1 cpu MHz : 2993.250 cache size : 1024 KB physical id : 0 siblings : 2 core id : 0 cpu cores : 1
where -- as far as I understood -- a `siblings' line with a value >1 denotes hyperthreading.
So, is it necessary to enable hyperthreading in BIOS, or does Linux just ignore that setting and utilizes the CPU's full capabilities anyhow?
TIA for any answer,
Joachim
-- =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- Joachim Schrod Email: jschrod@acm.org Roedermark, Germany
Can you post all of /proc/cpuinfo? You should at least a "ht" in the flags line? LDB
LDB wrote:
Joachim Schrod wrote:
I have a system with a Pentium P4 and an Intel D865GBF mainboard. The CPU has hyperthreading, but this is disabled in the BIOS. (The system got delivered that way. I bought it w/o any operating system.)
Can you post all of /proc/cpuinfo? You should at least a "ht" in the flags line?
Yes, I do. Here's the complete output: processor : 0 vendor_id : GenuineIntel cpu family : 15 model : 4 model name : Intel(R) Pentium(R) 4 CPU 3.00GHz stepping : 1 cpu MHz : 2993.250 cache size : 1024 KB physical id : 0 siblings : 2 core id : 0 cpu cores : 1 fdiv_bug : no hlt_bug : no f00f_bug : no coma_bug : no fpu : yes fpu_exception : yes cpuid level : 5 wp : yes flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe pni monitor ds_cpl cid xtpr bogomips : 5991.27 And also thanks for the other answers -- there are quite helpful. While I'm not too concerned about the security problem, I have to check if I have dual channel memory. (The board supports hyperthreading, that's checked already.) Cheers, Joachim -- =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- Joachim Schrod Email: jschrod@acm.org Roedermark, Germany
participants (7)
-
Bruce Marshall -
Joachim Schrod -
Jon Nelson -
LDB -
Michael W Cocke -
Randall R Schulz -
Steve Graegert