From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dirk Brandewie Subject: Re: v3.13.5 intel_pstate: cpufreq: __cpufreq_add_dev: ->get() failed Date: Tue, 11 Mar 2014 13:55:23 -0700 Message-ID: <531F783B.7010100@gmail.com> References: <531F6F50.1040209@gmail.com> <27921269.0Ejuc8iDoo@vostro.rjw.lan> <1679162.yVRSrpzkOW@vostro.rjw.lan> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Return-path: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=message-id:date:from:user-agent:mime-version:to:cc:subject :references:in-reply-to:content-type:content-transfer-encoding; bh=NSzNlLPw8BP6Af7VnsnpCYfxPsTkgX9Ym2KxBgAu2KE=; b=qjGj0cDC9IEAtDGQGoo0YVmZYrn7fWAIxndbC9dEoUyL27LLshdYkJt4sFOL6Rgn8X HGQaR6VwaEOZEa4NCISsNVGUul9Ts1tzm3QVTtGm2Xv9yQ6q3miGX77sMYtH770yDjjF a6H5mWPbVo103aXPYKyvXe4Ueb8p2KIL9wUzx00dYMbU+l2h4p/wE4WR0nsHoqTXDJcs OskE2Xjee6uLjaubBw7W4nzZ62Ywb7/463vvdVj1gxztbcHkhlZKRjAfUvPXA8WyCrAV NRmAq9LEEfXt+6ywJFy/g64L5aW3TJm8AL6HBWQ+sgF7aKifpbV69c1DyURpHf8d02lx KyKA== In-Reply-To: <1679162.yVRSrpzkOW@vostro.rjw.lan> Sender: cpufreq-owner@vger.kernel.org List-ID: Content-Type: text/plain; charset="us-ascii"; format="flowed" To: "Rafael J. Wysocki" Cc: dirk.brandewie@gmail.com, Patrik Lundquist , cpufreq@vger.kernel.org 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()