On Wednesday, March 12, 2014 12:07:03 AM Rafael J. Wysocki wrote: > On Tuesday, March 11, 2014 11:48:30 PM Rafael J. Wysocki wrote: > > On Tuesday, March 11, 2014 01:55:23 PM Dirk Brandewie wrote: > > > On 03/11/2014 01:57 PM, Rafael J. Wysocki wrote: > > > > On Tuesday, March 11, 2014 09:52:42 PM Rafael J. Wysocki wrote: > > > >> On Tuesday, March 11, 2014 01:17:20 PM Dirk Brandewie wrote: > > > >>> On 03/11/2014 01:20 PM, Rafael J. Wysocki wrote: > > > >>>> On Tuesday, March 11, 2014 10:58:59 AM Dirk Brandewie wrote: > > > >>>>> Hi Patrick, > > > >>>>> > > > >>>>> Sorry for the slow response you caught me taking a few days off :-) > > > >>>>> > > > >>>>> On 03/07/2014 07:49 AM, Patrik Lundquist wrote: > > > >>>>>> Hi, > > > >>>>>> > > > >>>>>> booting 3.13.5 on a dual socket Ivy Bridge-EP resulted in this error: > > > >>>>>> > > > >>>>>> [ 0.194139] smpboot: CPU0: Intel(R) Xeon(R) CPU E5-2687W v2 @ > > > >>>>>> 3.40GHz (fam: 06, model: 3e, stepping: 04) > > > >>>>>> ... > > > >>>>>> [ 0.246755] x86: Booting SMP configuration: > > > >>>>>> [ 0.250935] .... node #0, CPUs: #1 #2 #3 #4 #5 #6 #7 > > > >>>>>> [ 0.357648] .... node #1, CPUs: #8 #9 #10 #11 #12 #13 #14 #15 > > > >>>>>> [ 0.553293] x86: Booted up 2 nodes, 16 CPUs > > > >>>>>> [ 0.557666] smpboot: Total of 16 processors activated (108850.19 BogoMIPS) > > > >>>>>> ... > > > >>>>>> [ 5.210204] Intel P-state driver initializing. > > > >>>>>> [ 5.232407] Intel pstate controlling: cpu 0 > > > >>>>>> [ 5.253628] Intel pstate controlling: cpu 1 > > > >>>>>> [ 5.274899] cpufreq: __cpufreq_add_dev: ->get() failed > > > >>>>>> [ 5.294856] Intel pstate controlling: cpu 2 > > > >>>>>> [ 5.313553] Intel pstate controlling: cpu 3 > > > >>>>>> [ 5.332526] Intel pstate controlling: cpu 4 > > > >>>>>> [ 5.352347] Intel pstate controlling: cpu 5 > > > >>>>>> [ 5.372112] Intel pstate controlling: cpu 6 > > > >>>>>> [ 5.391097] Intel pstate controlling: cpu 7 > > > >>>>>> [ 5.410272] Intel pstate controlling: cpu 8 > > > >>>>>> [ 5.429092] Intel pstate controlling: cpu 9 > > > >>>>>> [ 5.447714] Intel pstate controlling: cpu 10 > > > >>>>>> [ 5.465872] Intel pstate controlling: cpu 11 > > > >>>>>> [ 5.482942] Intel pstate controlling: cpu 12 > > > >>>>>> [ 5.498414] Intel pstate controlling: cpu 13 > > > >>>>>> [ 5.513586] Intel pstate controlling: cpu 14 > > > >>>>>> [ 5.529200] Intel pstate controlling: cpu 15 > > > >>>>>> > > > >>>>>> CPU 1 is alive and well but missing the cpufreq driver. The system is > > > >>>>>> running fine otherwise. > > > >>>>> > > > >>>>> This is a regression introduced by commit > > > >>>>> da60ce9f2fa cpufreq: call cpufreq_driver->get() after calling ->init() > > > >>>> > > > >>>> So the problem is that ->get() may return 0 in intel_pstate and that causes > > > >>>> the core's _add function to abort? That would mean sample->freq equal to 0, > > > >>>> which shouldn't happen after intel_pstate_sample() called by intel_pstate_init_cpu(). > > > >>>> > > > >>>> Or am I missing anything? > > > >>>> > > > >>> > > > >>> The problem is that the core has been running less than 1% of the time based on > > > >>> the absolute values of aperf/mperf and the second sample has not been taken to > > > >>> get a more precise delta. > > > >>> > > > >>> I thought about running sample twice during init but didn't want to propose it > > > >>> until I made sure I was not going to break anything else. > > > >> > > > >> Well, ->setpolicy drivers are a special case anyway, so we can simply skip the > > > >> current frequency updates in __cpufreq_add_dev() and cpufreq_update_policy() > > > >> for them. > > > > > > > > In other words, we can do something like in the patch below I suppose? > > > > > > > > Rafael > > > > > > > > > > > > --- > > > > drivers/cpufreq/cpufreq.c | 4 ++-- > > > > 1 file changed, 2 insertions(+), 2 deletions(-) > > > > > > > > Index: linux-pm/drivers/cpufreq/cpufreq.c > > > > =================================================================== > > > > --- linux-pm.orig/drivers/cpufreq/cpufreq.c > > > > +++ linux-pm/drivers/cpufreq/cpufreq.c > > > > @@ -1137,7 +1137,7 @@ static int __cpufreq_add_dev(struct devi > > > > per_cpu(cpufreq_cpu_data, j) = policy; > > > > write_unlock_irqrestore(&cpufreq_driver_lock, flags); > > > > > > > > - if (cpufreq_driver->get) { > > > > + if (cpufreq_driver->get && !cpufreq_driver->setpolicy) { > > > > policy->cur = cpufreq_driver->get(policy->cpu); > > > > if (!policy->cur) { > > > > pr_err("%s: ->get() failed\n", __func__); > > > > @@ -2150,7 +2150,7 @@ int cpufreq_update_policy(unsigned int c > > > > * BIOS might change freq behind our back > > > > * -> ask driver for current freq and notify governors about a change > > > > */ > > > > - if (cpufreq_driver->get) { > > > > + if (cpufreq_driver->get && !cpufreq_driver->setpolicy) { > > > > new_policy.cur = cpufreq_driver->get(cpu); > > > > if (WARN_ON(!new_policy.cur)) { > > > > ret = -EIO; > > > > > > > or use has_target() > > > > Yes. > > > > Modified patch is appended. Patrik, can you please check if it helps? > > Well, actually, I think that checking ->setpolicy is more appropriate, because > both places modified by the patch above are before calling cpufreq_set_policy() > and that quite explicitly handles ->setpolicy drivers in a special way. > > It may be equivalent, but that's not obvious from the way the code is written. And by the way, it would be good to clarify this particular thing. Is having ->target set mutually exclusive with having ->setpolicy set? Rafael -- To unsubscribe from this list: send the line "unsubscribe cpufreq" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html