Messages in this thread | | | Date | Thu, 17 Oct 2013 15:24:36 +0000 | From | Christoph Lameter <> | Subject | Re: [PATCH] kmod: Run usermodehelpers only on cpus allowed for kthreadd |
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On Thu, 17 Oct 2013, Frederic Weisbecker wrote:
> > - /* We can run anywhere, unlike our parent keventd(). */ > > - set_cpus_allowed_ptr(current, cpu_all_mask); > > + /* We can run anywhere kthreadd can run */ > > + set_kthreadd_affinity(); > > If you really want your isolated CPUs to be undisturbed, you need this affinity to > be set before the creation of this usermode helper. Otherwise it's going to run to any random > place before you call the above function. > > Is there now way to control the kworker affinity which create this usermode helpers threads > instead?
The invocation is coming from keventd so the affinity seems to be set to a different cpu before we get the thread moved.
A tsc loop is running on the processor that gets hit by the usermodehelper spawns.
We see spawning by the tty notifier (when typing on a vt) as well as by a mellanox driver (periodically).
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