Re: [PATCH v9 1/2] Documentation: kdump: remind user of nr_cpus

From: "Zhou, Wenjian/åæå"
Date: Thu Aug 18 2016 - 20:57:16 EST


Hi Jonathan,

Thanks for your reply.

On 08/19/2016 01:18 AM, Jonathan Corbet wrote:
On Thu, 18 Aug 2016 11:11:46 +0800
Zhou Wenjian <zhouwj-fnst@xxxxxxxxxxxxxx> wrote:

Thank you for working to improve the documentation!

* We generally don' have to bring up a SMP kernel just to capture the
dump. Hence generally it is useful either to build a UP dump-capture
kernel or specify maxcpus=1 option while loading dump-capture kernel.
+ Note, though maxcpus always works, you should replace it by nr_cpus to
+ save memory if supported by the current ARCH, such as x86.

So, IMHO, this seems like the wrong place for this. I've just spent a bit
of time staring at kernel-parameters.txt, and there is no way for a
clueless user like me to know what the difference is between maxcpus= and
nr_cpus= would be. A far better patch would be to update the
documentation there to make that clear. Any chance you would be willing
to do that?

Then, rather than tacking an "ignore what you just read" note into
kdump.txt, it could maybe be rewritten to simply say what users should do?


I was also confused by maxcpus and nr_cpus before writing this patch.
I think it is a good choice to describe it in kernel-parameters.txt.

Then, only two things need to be done I think.
One is move the above description to maxcpus= in kernel-parameters.txt.
And the other is replace maxcpus with maxcpus/nr_cpus in kdump.txt.

How do you think?

--
Thanks
Zhou