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class=bodytextBlueBold>Linux* Issues with Hyper-Threaded
Technology</SPAN><BR><SPAN class=bodytextBlack>For Linux to make use of HT
Technology an SMP kernel must be installed. This is confirmed by the output of
uname -a, which shows the kernel version ending in SMP. The output of cat
/proc/cpuinfo (see below) will show the number of CPU's and their properties. HT
Technology is shown by the presence of the ht flag. If the computer BIOS
supports SMP (or an analogous option is activated in BIOS), the machine can be
used as an SMP system with Linux. When the SMP kernel is installed, it will seem
as if double the physical processors are available. At present the errata
kernels 2.4.9-21 and 2.4.9-31 have HT Technology support, but you have to pass
"acpismp=force" on the kernel command line to enable
it.</SPAN><BR><BR><BR><BR><IMG height=1
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<TD noWrap width="100%"><TT><CODE
xmlns:UrlReplace="urn:PlatformDocument"><BR>> $cat
/proc/cpuinfo<BR>> processor : 0<BR>> vendor_id :
GenuineIntel<BR>> cpu family : 15<BR>> model : 1<BR>> model name
: Intel(R) Pentium(R) 4 CPU 1.70GHz<BR>> stepping : 2<BR>> cpu MHZ :
1694.907<BR>> cache size : 256 KB<BR>> fdiv_bug : no<BR>> hlt_bug
: no<BR>> f00f_bug : no<BR>> coma_bug : no<BR>> fpu : yes<BR>>
fpu_exception : yes<BR>> cpuid level : 2<BR>> wp : yes<BR>> flags
: fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge<BR>> mca cmov
pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm<BR>> bogomips :
3381.65<BR>><BR><BR></CODE></TT></TD></TR></TBODY></TABLE>
<DIV><IMG height=1
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border=0><BR><BR><A name=section_2></A><BR><SPAN class=bodytextBlack>The Linux
2.4 kernel will not be developed to take an active advantage of HT Technology
and patches may be required to fix some possible problems. Rusty Russell (a
Linux developer) mentions: "The hyperthreading issue... is likely to throw a new
set of complications into the mix. A processor which does hyperthreading looks
like two independent CPUs, but it [processes] should not be scheduled [by the
scheduler] as such - it is better to divide process across real (hardware)
processors first."</SPAN><BR><BR><SPAN class=bodytextBlack>Work is underway in
the Linux community to add HT Technology patches to the 2.4 release of the Linux
kernel. HT Technology changes to Linux are being exploited by Carrier Grade
Linux Change Project under the ODSL (see below). HT Technology offers
performance enhancement potentials that are a prime requirement of the carrier
grade environment. Active utilization of HT Technology will likely appear in the
standard 2.5 Linux kernel, although it has not yet been placed into the
development queue due to prerequisite work being done.</SPAN><BR><IMG height=1
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border=0><BR><BR><A name=section_3></A><SPAN class=bodytextBlueBold>Linux HT
Technology Capable Compilers</SPAN><BR><SPAN class=bodytextBlack>The Intel Linux
C++ Compiler 6.0 has increased levels of Linux and industry standards support
that provide improved compatibility with GNU C, broader support of Linux
distributions, support for the C++ ABI object model and GNU inline ASM for IA32.
- The Intel C++ Compiler supports OpenMP API version 1.0 and performs code
transformation for shared memory parallel programming. The Intel compiler
supports multi-threaded application development and debugging, with support for
OpenMP 1.0 for C and new support for OpenMP 1.0 for C++. This makes it fully
capable of designing HT Technology enabled applications on HT Technology enabled
hardware.</SPAN><BR></DIV>
<DIV>Taken from Intel's website, search enable hyperthreading, linux</DIV>
<DIV> </DIV>
<DIV>Jon</DIV>
<DIV> </DIV>
<DIV>Jon L. Miller, MCNE, CNS, ASE<BR>Director/Sr Systems Consultant<BR>MMT
Networks Pty Ltd<BR><A
href="http://www.mmtnetworks.com.au">http://www.mmtnetworks.com.au</A></DIV>
<DIV> </DIV>
<DIV>"I don't know the key to success, but the key to failure<BR> is trying
to please everybody." -Bill Cosby</DIV>
<DIV> </DIV>
<DIV> </DIV>
<DIV><BR>>>> smclevie@ozemail.com.au 2:44:35 pm 10/12/2003
>>><BR>Hi all,<BR><BR>I wonder if someone could inform me of the
necessary steps to enable <BR>hyperthreading (P4 2.4G Pentium)?<BR><BR>I thought
I had enabled the option in a kernel build ...<BR><BR>I would like to see two
tuxes at the top of screen also.<BR><BR>Thank you,<BR><BR>Steve.
<BR><BR><BR>_______________________________________________<BR>plug mailing
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