Messages in this thread | | | Date | Thu, 11 Apr 2013 14:00:56 -0700 | From | "Paul E. McKenney" <> | Subject | Re: [PATCH documentation 2/2] kthread: Document ways of reducing OS jitter due to per-CPU kthreads |
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On Thu, Apr 11, 2013 at 01:09:28PM -0700, Randy Dunlap wrote: > On 04/11/13 11:40, Paul E. McKenney wrote: > > On Thu, Apr 11, 2013 at 10:18:26AM -0700, Randy Dunlap wrote: > >> On 04/11/2013 09:05 AM, Paul E. McKenney wrote: > >>> From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> > >>> > >>> The Linux kernel uses a number of per-CPU kthreads, any of which might > >>> contribute to OS jitter at any time. The usual approach to normal > >>> kthreads, namely to affinity them to a "housekeeping" CPU, does not > >> > >> ugh. to affine them > > > > How about s/affinity/bind/ instead? > > Yes, that's good. > > >>> work with these kthreads because they cannot operate correctly if moved > >>> to some other CPU. This commit therefore lists ways of controlling OS > >>> jitter from the Linux kernel's per-CPU kthreads. > >>> > >>> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> > >>> Cc: Frederic Weisbecker <fweisbec@gmail.com> > >>> Cc: Steven Rostedt <rostedt@goodmis.org> > >>> Cc: Borislav Petkov <bp@alien8.de> > >>> Cc: Arjan van de Ven <arjan@linux.intel.com> > >>> Cc: Kevin Hilman <khilman@linaro.org> > >>> Cc: Christoph Lameter <cl@linux.com> > >>> --- > >>> Documentation/kernel-per-CPU-kthreads.txt | 159 ++++++++++++++++++++++++++++++ > >>> 1 file changed, 159 insertions(+) > >>> create mode 100644 Documentation/kernel-per-CPU-kthreads.txt > >>> > >>> diff --git a/Documentation/kernel-per-CPU-kthreads.txt b/Documentation/kernel-per-CPU-kthreads.txt > >>> new file mode 100644 > >>> index 0000000..495dacf > >>> --- /dev/null > >>> +++ b/Documentation/kernel-per-CPU-kthreads.txt > >>> @@ -0,0 +1,159 @@ > >>> +REDUCING OS JITTER DUE TO PER-CPU KTHREADS > >>> + > >>> + > >>> +Name: irq/%d-%s > >>> +Purpose: Handle threaded interrupts. > >>> +To reduce corresponding OS jitter, do the following: > >>> +1. Use irq affinity to force the irq threads to execute on > >>> + some other CPU. > >> > >> It would be very nice to explain here how that is done. > > > > Documentation/IRQ-affinity.txt > > > > I added a pointer to this near the beginning. > > > > Good. > > > Thank you for your review and comments! Given my rationale above, > > are you still comfortable with my applying your Reviewed-by? > > Sure. Thanks. > > >> Reviewed-by: Randy Dunlap <rdunlap@infradead.org>
I have added your Reviewed-by, thank you again!
Thanx, Paul
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