Messages in this thread |  | | Date | Wed, 9 Apr 2014 11:29:50 -0400 | From | Steven Rostedt <> | Subject | Re: nohz problem with idle time on old hardware |
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On Wed, 9 Apr 2014 20:50:59 +0530 Viresh Kumar <viresh.kumar@linaro.org> wrote:
> On 9 April 2014 20:01, Steven Rostedt <rostedt@goodmis.org> wrote: > > Ouch! You are correct, this part of the patch makes no sense. That's > > what I get for reviewing a patch and not looking at all the code around > > the changes. (another kernel developer hangs head in shame :-( ) > > > > I think that if statement should be nuked. > > Hmm, my opinion differs here :) > > If we completely remove this statement, we will run > tick_nohz_switch_to_nohz() even if nohz is not enabled. And check for > enabled must stay.
Do we? This is only called by tick_check_oneshot_change() which has the following:
int tick_check_oneshot_change(int allow_nohz) { struct tick_sched *ts = &__get_cpu_var(tick_cpu_sched);
if (!test_and_clear_bit(0, &ts->check_clocks)) return 0;
if (ts->nohz_mode != NOHZ_MODE_INACTIVE) return 0;
if (!timekeeping_valid_for_hres() || !tick_is_oneshot_available()) return 0;
if (!allow_nohz) return 1;
tick_nohz_switch_to_nohz(); return 0; }
How often does it make it to that last check?
-- Steve
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