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From: Bill Davidsen <davidsen@tmr.com>
To: Justin Banks <justinb@bakbone.com>
Cc: "Miller, Mike (OS Dev)" <Mike.Miller@hp.com>,
	linux-kernel@vger.kernel.org
Subject: Re: FW: Linux question
Date: Fri, 07 Mar 2008 13:43:45 -0500	[thread overview]
Message-ID: <47D18CE1.7050206@tmr.com> (raw)
In-Reply-To: <20080306203841.GA4282@bleen.domain.actdsltmp>

Justin Banks wrote:
> Miller, Mike (OS Dev) wrote
>> Is there a way in to limit the kernel to seeing only the cores on a
>> single processor and ignore all other processor cores (eg. leave
>> them in HALT)?
> 
> Can't you just echo 0 into /sys/devices/system/cpu/cpuN/online where the
> /sys/devices/system/cpu/cpuN/topology/physical_package_id isn't the one
> you want to keep online?
> 
Here's an interesting question, why isn't there an "online" file for 
each CPU?

Example:

posidon:davidsen> l /sys/devices/system/cpu/cpu?
/sys/devices/system/cpu/cpu0:
total 0
drwxr-xr-x 5 root    0 Feb  7 12:57 cache
drwxr-xr-x 3 root    0 Mar  7 13:28 cpufreq
-r-------- 1 root 4096 Mar  7 13:28 crash_notes
drwxr-xr-x 2 root    0 Mar  7 13:28 microcode
drwxr-xr-x 2 root    0 Mar  7 13:28 topology

/sys/devices/system/cpu/cpu1:
total 0
drwxr-xr-x 5 root    0 Feb  7 12:57 cache
drwxr-xr-x 3 root    0 Mar  7 13:28 cpufreq
-r-------- 1 root 4096 Mar  7 13:28 crash_notes
drwxr-xr-x 2 root    0 Mar  7 13:28 microcode
-rw-r--r-- 1 root 4096 Mar  7 13:28 online
drwxr-xr-x 2 root    0 Mar  7 13:28 topology


-- 
Bill Davidsen <davidsen@tmr.com>
   "We have more to fear from the bungling of the incompetent than from
the machinations of the wicked."  - from Slashdot

  reply	other threads:[~2008-03-07 18:39 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-03-06 19:33 Miller, Mike (OS Dev)
2008-03-06 19:51 ` Cyrill Gorcunov
2008-03-06 20:38 ` Justin Banks
2008-03-07 18:43   ` Bill Davidsen [this message]
2008-03-07 19:13     ` Justin Banks
2008-03-07 19:14     ` Andi Kleen
2008-03-08 17:07       ` Bill Davidsen

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