Messages in this thread | | | Date | Sun, 20 Oct 2013 18:00:24 +0000 | From | Christoph Lameter <> | Subject | Re: [PATCH] kmod: Run usermodehelpers only on cpus allowed for kthreadd |
| |
On Fri, 18 Oct 2013, Frederic Weisbecker wrote:
> Makes sense yeah. In fact what I'm mostly concerned about is that we should > set the affinity of __call_usermodehelper threads through inheritance from > a parent rather than making it setting its affinity itself. Because in the latter case, > the usermodehelper thread can run anywhere until it sets its affinity. Whether > this little window of global affinity is short or not, this defeats the initial purpose > of this patch that is about isolating CPUs and having them undisturbed. > > May be we can do that by setting the affinity of the "khelper" workqueue?
The "parent" for usemodehelper in this case is keventd. The worker queue item is triggered on a particular processor and thats fine because that is the result of an OS action or a device irq action. These can already be avoided. What is not ok is that a process makes a move onto a hardware thread where we want to have the least OS holdoffs possible.
Setting it via khelper would be fine. Any objections?
| |