Messages in this thread | | | Date | Thu, 23 Jan 2014 08:32:35 -0500 | Subject | Re: [PATCH 13/15] sched: Use a static_key for sched_clock_stable | From | Josh Boyer <> |
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On Thu, Jan 23, 2014 at 4:48 AM, Peter Zijlstra <peterz@infradead.org> wrote: > On Wed, Jan 22, 2014 at 10:17:40PM +0100, Markus Trippelsdorf wrote: >> Yes. Thanks Peter. >> > > Ah much simpler patch that should have the same effect:
This fixes the issue on my baremetal i7 machine as well.
josh
> --- > Subject: sched/x86/tsc: Initialize multiplier to 0 > From: Peter Zijlstra <peterz@infradead.org> > Date: Wed, 22 Jan 2014 22:08:14 +0100 > > Since we keep the clock value linearly continuous on frequency change, > make sure the initial multiplier is 0, such that out initial value is > 0. Without this we compute the initial value at whatever the TSC has > managed to reach since power-on. > > Fixes: 20d1c86a57762 ("sched/clock, x86: Rewrite cyc2ns() to avoid the need to disable IRQs") > Cc: lenb@kernel.org > Cc: rjw@rjwysocki.net > Cc: Eliezer Tamir <eliezer.tamir@linux.intel.com> > Cc: rui.zhang@intel.com > Cc: jacob.jun.pan@linux.intel.com > Cc: Mike Galbraith <bitbucket@online.de> > Cc: Ingo Molnar <mingo@kernel.org> > Cc: hpa@zytor.com > Cc: paulmck@linux.vnet.ibm.com > Cc: Thomas Gleixner <tglx@linutronix.de> > Cc: John Stultz <john.stultz@linaro.org> > Cc: Andy Lutomirski <luto@amacapital.net> > Cc: Arjan van de Ven <arjan@linux.intel.com> > Cc: Sasha Levin <sasha.levin@oracle.com> > Cc: dyoung@redhat.com > Reported-by: Markus Trippelsdorf <markus@trippelsdorf.de> > Signed-off-by: Peter Zijlstra <peterz@infradead.org> > --- > arch/x86/kernel/tsc.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > --- a/arch/x86/kernel/tsc.c > +++ b/arch/x86/kernel/tsc.c > @@ -180,7 +180,7 @@ static void cyc2ns_write_end(int cpu, st > > static void cyc2ns_data_init(struct cyc2ns_data *data) > { > - data->cyc2ns_mul = 1U << CYC2NS_SCALE_FACTOR; > + data->cyc2ns_mul = 0; > data->cyc2ns_shift = CYC2NS_SCALE_FACTOR; > data->cyc2ns_offset = 0; > data->__count = 0; > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/
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