Thanks for the reply! <br>I am looking for a little more detail.<br><br>Thanks<br><br><br><div class="gmail_quote">On Tue, Aug 16, 2011 at 10:26 PM, Vladimir Murzin <span dir="ltr"><<a href="mailto:murzin.v@gmail.com">murzin.v@gmail.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;"><div><div></div><div class="h5">On Wed, Aug 17, 2011 at 9:14 AM, Vaibhav Jain <<a href="mailto:vjoss197@gmail.com">vjoss197@gmail.com</a>> wrote:<br>
> Hi,<br>
><br>
> I need to know the difference between making a cpu logically offline<br>
> and physically offline. I have read that the following command<br>
><br>
> $ echo 0 > /sys/device/system/cpu/<cpu number>/online<br>
><br>
> makes a cpu logically offline. It frees the cpu from interrupts and migrates<br>
> running processes.<br>
> But then what does it mean to make a cpu physically offline ?<br>
> I referred to following article :<br>
><br>
> <a href="http://www.kernel.org/doc/Documentation/cpu-hotplug.txt" target="_blank">http://www.kernel.org/doc/Documentation/cpu-hotplug.txt</a><br>
><br>
> Here is the relevant excerpt :<br>
><br>
> Q: Does hot-add/hot-remove refer to physical add/remove of cpus?<br>
> A: The usage of hot-add/remove may not be very consistently used in the<br>
> code.<br>
> CONFIG_HOTPLUG_CPU enables logical online/offline capability in the kernel.<br>
> To support physical addition/removal, one would need some BIOS hooks and<br>
> the platform should have something like an attention button in PCI hotplug.<br>
> CONFIG_ACPI_HOTPLUG_CPU enables ACPI support for physical add/remove of<br>
> CPUs.<br>
><br>
> Please help!<br>
><br>
> Thanks<br>
> Vaibhav Jain<br>
><br>
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><br>
><br>
Hi Vaibhav!<br>
<br>
I think physical CPU hot-plug is a capability to plug in and out<br>
processing device (CPU) on running machine. Logical CPU hot-plug is a<br>
capability to add on and remove out already available processing units<br>
(CPU s or cores) under SMP domain of OS.<br>
<br>
P.S. Sorry for my weak English.<br>
</blockquote></div><br>