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Subject: RE: detecting hyperthreading in linux 2.4.19
Date: Thu, 9 Jan 2003 14:29:41 -0800
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From: "Kamble, Nitin A" <nitin.a.kamble@intel.com>
To: <lunz@falooley.org>, <jamesclv@us.ibm.com>, <linux-kernel@vger.kernel.org>
Cc: "Nakajima, Jun" <jun.nakajima@intel.com>,
       "Saxena, Sunil" <sunil.saxena@intel.com>,
       "Mallick, Asit K" <asit.k.mallick@intel.com>,
       "Schlobohm, Bruce" <bruce.schlobohm@intel.com>
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Hi James,
I have posted a patch for this on LKML. Please have look at:
http://www.uwsg.indiana.edu/hypermail/linux/kernel/0301.0/1886.html
http://www.uwsg.indiana.edu/hypermail/linux/kernel/0301.0/1887.html

It should solve the problem you are trying to solve.

Nitin

> -----Original Message-----
> From: Jason Lunz [mailto:lunz@falooley.org]
> Sent: Thursday, January 09, 2003 1:57 PM
> To: linux-kernel@vger.kernel.org
> Subject: Re: detecting hyperthreading in linux 2.4.19
> 
> jamesclv@us.ibm.com said:
> > I don't know of any way to do this in userland.  The whole point is
> > that the sibling processors are supposed to look like real ones.
> 
> That's unfortunately not always true. I'm writing a program that will
> run on a system that will be doing high-load routing. Testing has
shown
> that we get better performance when binding each NIC's interrupts to a
> separate physical processor using /proc/irq/*/smp_affinity (especially
> when all the interrupts would hit the first CPU, another problem i've
> yet to address). That only works for real processors, though, not
> HT siblings.
> 
> I'm writing a program to run on machines of unknown (by me)
> configuration, that will spread out the NIC interrupts appropriately.
> So userspace needs to know the difference, at least until interrupts
can
> be automatically distributed by the kernel in a satisfactory way.
> 
> Jason
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