Messages in this thread | | | Date | Wed, 29 Jan 2014 09:56:20 -0800 | Subject | Re: [PATCH] [RFC] timekeeping: Rework frequency adjustments to work better w/ nohz | From | John Stultz <> |
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On Tue, Jan 28, 2014 at 9:58 AM, Richard Cochran <richardcochran@gmail.com> wrote: > I tested for a regression using the patched kernel with the nohz=off > command line option... > > On Mon, Jan 13, 2014 at 10:15:18AM -0800, John Stultz wrote: >> On 01/13/2014 09:51 AM, Richard Cochran wrote: >> > >> > - Linux 3.12.7-nohz-plain-20140106 nohz-plain.log >> > - Linux 3.12.7-nohz-plain-20140106 NOHZ=OFF periodic-plain.log >> > - Linux 3.12.7-nohz-fix-20140106-00001-gd753140 nohz-fix.log > > Regression check: > > - Linux homeboy 3.12.7-nohz-fix-20140106-00001-gd753140 NOHZ=OFF > nohz-fix-periodic.log > >> > The performance in the log files as reflected in the clock offset is >> > summarized in this table. The values are in nanoseconds. >> > >> > | | periodic-plain | nohz-fix | nohz-plain | >> > |---------+----------------+---------------+---------------| >> > | minimum | -1.599000e+03 | -1.051000e+03 | -5.373700e+04 | >> > | maximum | +1.311000e+03 | +1.048000e+03 | +6.389500e+04 | >> > | mean | +9.880240e-02 | -7.747305e+01 | +1.597904e+01 | >> > | stddev | +4.610021e+02 | +3.960978e+02 | +1.491263e+04 | > > Comparing the nohz=off case with and without the patch, the three hour > test looks like this. > > | | periodic-plain | nohz-fix-periodic | > |---------+----------------+-------------------+ > | minimum | -1.599000e+03 | -1.427000e+03 | > | maximum | +1.311000e+03 | +1.279000e+03 | > | mean | +9.880240e-02 | -2.710778e+01 | > | stddev | +4.610021e+02 | +3.974372e+02 | > >> > http://linuxptp.sourceforge.net/nohz-fix/current_nohz.png >> > http://linuxptp.sourceforge.net/nohz-fix/periodic_vs_fix.png > > I also made a third graph showing before and after the patch. > > http://linuxptp.sourceforge.net/nohz-fix/nohz_regression.png > >> If you do get a chance to look again, I'd also be interested if running >> with nohz=off w/ the fix doesn't show any regression compared to the >> unmodified nohz=off case. > > Looks like there is no regression.
That's great to hear! Looks like we might be able to queue it for 3.15...
Thanks so much again for the detailed testing! I really appreciate it!
thanks -john
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