RE: [discuss] [PATCH] Export cpu topology for IA32 and x86_64 by sysfs

[Zhang, Yanmin]

>>-----Original Message-----
>>From: Andi Kleen [mailto:ak@xxxxxxx]
>>Sent: 2005年12月14日 11:51
>>To: Zhang, Yanmin
>>Cc: linux-kernel@xxxxxxxxxxxxxxx; discuss@xxxxxxxxxx; Pallipadi, Venkatesh
>>Subject: Re: [discuss] [PATCH] Export cpu topology for IA32 and x86_64 by sysfs
>>
>>On Wed, Dec 14, 2005 at 11:11:00AM +0800, Zhang, Yanmin wrote:
>>> The patch exports the cpu topology info through sysfs on ia32/x86_64
>>> machines. The info is similar to /proc/cpuinfo.
>>>
>>> The exported items are:
>>> /sys/devices/system/cpu/cpuX/topology/physical_package_id(representing
>>> the physical package id of  cpu X)
>>> /sys/devices/system/cpu/cpuX/topology/core_id (representing the cpu core
>>> id  to cpu X)
>>> /sys/devices/system/cpu/cpuX/topology/thread_siblings (representing the
>>> thread siblings to cpu X)
>>> /sys/devices/system/cpu/cpuX/topology/core_siblings (represeting the
>>> core siblings to cpu X)
>>
>>Hmm, I'm not sure it is that useful. Did someone decide to move
>>all information from cpuinfo into sysfs?
It's more convenient for shell scripts to get cpu topology info from sysfs.

>>
>>And if it's done I think it needs Documentation somewhere.
There is no appropriate file to write down the info under Documentation.

>>
>>Anyways, the notifier is wrong. You need to handle CPU_UP_CANCELLED
>>too.
No. The node and related data are created/registered only when cpu is CPU_ONLINE. If CPU_UP_CANCELED is delivered to the notifier, the cpu is not online, and its node is not registered, so we needn't do anything when CPU_UP_CANCELED.

>>
>>And you could probably shrink the code size of the show function
>>in half by switching data instead of functions.
I don't quite understand what you said. My patch just uses the attribute address (a kind of data, not function) as parameter. If the function needs to be shrunken, I think I have to define a sub function per attribute which causes even longer code size.

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