Re: [PATCH 4/6] nohz: support PR_DATAPLANE_QUIESCE

On Fri, May 08, 2015 at 01:58:45PM -0400, Chris Metcalf wrote:

This prctl() flag for PR_SET_DATAPLANE sets a mode that requires the
kernel to quiesce any pending timer interrupts prior to returning
to userspace.  When running with this mode set, sys calls (and page
faults, etc.) can be inordinately slow.  However, user applications
that want to guarantee that no unexpected interrupts will occur
(even if they call into the kernel) can set this flag to guarantee
that semantics.

Currently people hot-unplug and hot-plug the CPU to do this. Obviously
that's a wee bit horrible :-)

Not sure if a prctl like this is any better though. This is a CPU
properly not a process one.

ISTR people talking about 'quiesce' sysfs file, along side the hotplug
stuff, I can't quite remember.