Re: [RFC, 3/7] NUMA hotplug emulator

From: Haicheng Li
Date: Thu May 13 2010 - 22:13:39 EST


Dave Hansen wrote:
On Thu, 2010-05-13 at 09:55 -0700, Greg KH wrote:
Add a sysfs entry "probe" under /sys/devices/system/node/:

- to show all fake offlined nodes:
$ cat /sys/devices/system/node/probe

- to hotadd a fake offlined node, e.g. nodeid is N:
$ echo N > /sys/devices/system/node/probe
As you are trying to add a new sysfs file, please create the matching
Documentation/ABI/ file as well.

Also note that sysfs files are "one value per file", which I don't think
this file follows, right?

I think in this case, it was meant to be a list of acceptable parameters
rather than a set of values, kinda like /sys/power/state.

Right.

Instead, I guess we could have:

/sys/devices/system/node/probeable/3
/sys/devices/system/node/probeable/43
/sys/devices/system/node/probeable/65
/sys/devices/system/node/probeable/5145

and the knowledge that you need to pick one of those to echo
into /sys/devices/system/node/probe.

I think this way would make things complex if we just want to show user which node could be hotadded.

But, it's a lot more self
explanatory if you 'cat /sys/devices/system/node/probe', and then pick
one of those to echo back into the file.

agreed.

Seems like a decent place to violate the "rule". :)



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