Messages in this thread | | | Date | Thu, 11 Apr 2013 13:09:28 -0700 | From | Randy Dunlap <> | Subject | Re: [PATCH documentation 2/2] kthread: Document ways of reducing OS jitter due to per-CPU kthreads |
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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>
-- ~Randy
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