Re: [PATCH] stop on cpu lost

[Randy.Dunlap]

On Fri, 23 Jun 2006 01:05:50 +0900 KAMEZAWA Hiroyuki wrote:

> On Thu, 22 Jun 2006 08:45:55 -0700 (PDT)
> Christoph Lameter <clameter@xxxxxxx> wrote:
> 
> > On Thu, 22 Jun 2006, Randy.Dunlap wrote:
> > 
> > > Sounds much better than just killing the process.
> > 
> > Right and having active interrupts or devices using that processor should 
> > also stop offlining a processor.
> > 
> > So just remove everything from a processor before offlining. If you cannot 
> > remove all users then the processor cannot be offlined.
> > 
> Hm..
> Then, there is several ways to manage this sitation.
> 
> 1. migrate all even if it's not allowed by users
> 2. kill mis-configured tasks.

I would claim that the tasks are not misconfigured,
but that the admin misconfigured the hardware (CPU).

> 3. stop ...
> 4. cancel cpu-hot-removal.
> 
> I just don't like "1". 

I like it better than 2.

> I discussed this problem with my colleagues before sending patch,
> one said "4" seems regular way but another said "4" is bad.
> 
> I sent a patch for "4" in the first place but Andi Kleen said it's bad.
> As he said, I'm handling the problem for which I can't find a good answer :(
> 
> my point is that "1" is bad.

Sounds like we are getting nowhere.  The sysctl knob might
have to be the answer.

---
~Randy
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