Question about watchdog

[greg@kroah.com (Greg KH)]

On Mon, Jul 02, 2018 at 08:58:16AM +0100, Justin Skists wrote:
> 
> > On 01 July 2018 at 13:44 bing zhu <zhubohong12@gmail.com> wrote:
> > 
> > 
> > Dear Sir/Ma'am
> > Thank you for your time ,i'm a student new to linux kernel.at present ,i'd
> > like to create a kernel thread
> > say use kthread_create func ,my question is :how can i make this thread to
> > run on a cpu and never get switched or scheduled , there is a
> > while(1).....structure in that thread i need it to do work . at present i
> > comes with errors like "NMI watchdog: BUG: soft lockup - CPU#0 stuck for
> > 23s! [test thread :1881]",i understand there is a watchdog but is there
> > anyway i can feed the dog myself and let my thread have cpu as much as i
> > want ?
> 
> Yowsers! Why would you want to do that? The whole idea of a watchdog is
> to prevent threads hogging the CPU for a long time. Linux is a multi-user,
> multi-process, pre-emptive operating system. It needs to share. :-)

Not true, Linux can take a cpu, remove itself from it, and run a single
process if needed, just fine.  It's a great operating system for such a
thing.

You just have to use the apis we have for this already, it's been
possible to do this for many years now.

As for why you would want to do this within the kernel itself, well, I
can understand that need for some situations, and it is possible to do
as well, just use the correct api and all is fine (no, I can't remember
what it is at the moment, sorry...)

greg k-h