Some MSR values for the troubling CPU 1 (I haven't rebooted since the error): Min P-state: 12 Max P-state: 34 Turbo P-state: 40 TSC: 1105403635263536 APERF: 153644110734887 MPERF: 142432205366417 Maybe a bit surprising that APERF is larger than MPERF since turbo isn't working for CPU 1. The APERF/MPERF ratio should be close to 1.0 at boot time. Are the counters reset by Linux? Can there be a race condition that throws off the ratio? On 10 March 2014 06:23, Viresh Kumar <viresh.kumar@xxxxxxxxxx> wrote: > Cc'ing relevant people.. > > On Fri, Mar 7, 2014 at 11:49 PM, Patrik Lundquist > <patrik.lundquist@xxxxxxxxx> 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. >> >> Looking closer at the problem gives that intel_pstate_init_cpu() is >> successful but intel_pstate_get(), which is called right after by >> cpufreq, fails. >> >> Since all_cpu_data[1] is initialized it gives that sample->freq must >> be zero. So the bug should be in intel_pstate_calc_busy() which >> incorrectly sets sample->freq to zero. >> >> I guess cpu->pstate.max_pstate == 4000000 since that's what >> cpuinfo_max_freq and scaling_max_freq is on the other cores. >> >> So the error is likely that core_pct is calculated to 0 in >> intel_pstate.c:intel_pstate_calc_busy(): >> >> core_pct = div64_u64(int_tofp(sample->aperf * 100), >> sample->mperf); >> >> >> >> Might be fixed by this commit but should be backported in that case: >> >> commit fcb6a15c2e7e76d493e6f91ea889ab40e1c643a4 >> Author: Dirk Brandewie <dirk.j.brandewie@xxxxxxxxx> >> Date: Mon Feb 3 08:55:31 2014 -0800 >> >> intel_pstate: Take core C0 time into account for core busy calculation >> >> >> >> My options to explore the problem further by backporting patches and >> continuous reboots are a bit limited at the moment. >> >> Regards, >> Patrik >> -- >> 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 -- 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
