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Date: Wed, 2 Apr 2014 16:31:31 -0400 From: Paul Gortmaker <paul.gortmaker@...driver.com> To: "Brown, Len" <len.brown@...el.com> CC: "WYSOCKI, RAFAL" <rafael.j.wysocki@...el.com>, Arne Bockholdt <linux-kernel@...kholdt.com>, Jiang Liu <jiang.liu@...ux.intel.com>, "x86@...nel.org" <x86@...nel.org>, "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org> Subject: Re: Regression in intel_idle on Avaton/Rangely Mohon Peak board [Re: Regression in intel_idle on Avaton/Rangely Mohon Peak board] On 02/04/2014 (Wed 16:01) Paul Gortmaker wrote: > On 14-04-01 05:59 PM, Brown, Len wrote: > >> I've got an eval board with a 1.7GHz Avaton/C2000 that hangs at boot > >> shortly after the idle driver registration -- typically 1/2 dozen > >> dmesg lines later, around rtc init, or net stack init. > > > > Paul, > > Please boot the failing board with "intel_idle.max_cstate=0" > > to disable intel_idle entirely, and then show the C-states > > exported by acpi_idle, that predumably, are stable on both boards: > > > > dmesg | grep idle > > grep . /sys/devices/system/cpu/cpu0/cpuidle/*/* > > > > Then go back and boot with "intel_idle.max_cstate=N" > > where N is incremented by 1 until when the system fails > > and note the largest N that still works. > > The dying board works for N=1, fails for N=2. > > root@...alhost:/sys/devices/system/cpu/cpuidle# grep . * > current_driver:intel_idle > current_governor_ro:menu > root@...alhost:/sys/devices/system/cpu/cpuidle# dmesg|grep idle > [ 0.000000] Command line: BOOT_IMAGE=/boot/bzImage-current console=tty0 noinitrd root=/dev/sda4 rw ip=dhcp selinux=0 enforcing=0 intel_idle.max_cstate=1 > [ 0.000000] Kernel command line: BOOT_IMAGE=/boot/bzImage-current console=tty0 noinitrd root=/dev/sda4 rw ip=dhcp selinux=0 enforcing=0 intel_idle.max_cstate=1 > [ 0.000000] RCU dyntick-idle grace-period acceleration is enabled. > [ 0.217203] cpuidle: using governor ladder > [ 0.217309] cpuidle: using governor menu > [ 0.840598] intel_idle: MWAIT substates: 0x33000020 > [ 0.840662] intel_idle: v0.4 model 0x4D > [ 0.840668] intel_idle: lapic_timer_reliable_states 0x2 > [ 0.840673] intel_idle: max_cstate 1 reached > root@...alhost:/sys/devices/system/cpu/cpuidle# ...and the working board differs in reliable states, and it never prints out max_cstate reached either. Here are the data sets for no boot arg, and N=1 and N=2 from the working board with newer bios: ---------------- no bootarg --------------------- root@...alhost:/sys/devices/system/cpu/cpuidle# dmesg|grep idle [ 0.000000] RCU dyntick-idle grace-period acceleration is enabled. [ 0.220217] cpuidle: using governor ladder [ 0.220323] cpuidle: using governor menu [ 0.877519] intel_idle: MWAIT substates: 0x33000020 [ 0.877524] intel_idle: v0.4 model 0x4D [ 0.877528] intel_idle: lapic_timer_reliable_states 0xffffffff root@...alhost:/sys/devices/system/cpu/cpuidle# grep . * current_driver:intel_idle current_governor_ro:menu root@...alhost:/sys/devices/system/cpu/cpuidle# --------------- N=1 ---------------- root@...alhost:/sys/devices/system/cpu/cpuidle# dmesg|grep idle [ 0.000000] Command line: BOOT_IMAGE=/boot/bzImage-current console=tty0 noinitrd root=/dev/sda4 rw ip=dhcp selinux=0 enforcing=0 intel_idle.max_cstate=1 [ 0.000000] Kernel command line: BOOT_IMAGE=/boot/bzImage-current console=tty0 noinitrd root=/dev/sda4 rw ip=dhcp selinux=0 enforcing=0 intel_idle.max_cstate=1 [ 0.000000] RCU dyntick-idle grace-period acceleration is enabled. [ 0.220169] cpuidle: using governor ladder [ 0.220276] cpuidle: using governor menu [ 0.786569] intel_idle: MWAIT substates: 0x33000020 [ 0.786574] intel_idle: v0.4 model 0x4D [ 0.786578] intel_idle: lapic_timer_reliable_states 0xffffffff [ 0.786582] intel_idle: max_cstate 1 reached root@...alhost:/sys/devices/system/cpu/cpuidle# grep . * current_driver:intel_idle current_governor_ro:menu root@...alhost:/sys/devices/system/cpu/cpuidle# --------------- N=2 ---------------- root@...alhost:~# cd /sys/devices/system/cpu/cpuidle/ root@...alhost:/sys/devices/system/cpu/cpuidle# dmesg|grep idle [ 0.000000] Command line: BOOT_IMAGE=/boot/bzImage-current console=tty0 noinitrd root=/dev/sda4 rw ip=dhcp selinux=0 enforcing=0 intel_idle.max_cstate=2 [ 0.000000] Kernel command line: BOOT_IMAGE=/boot/bzImage-current console=tty0 noinitrd root=/dev/sda4 rw ip=dhcp selinux=0 enforcing=0 intel_idle.max_cstate=2 [ 0.000000] RCU dyntick-idle grace-period acceleration is enabled. [ 0.220415] cpuidle: using governor ladder [ 0.220524] cpuidle: using governor menu [ 0.877641] intel_idle: MWAIT substates: 0x33000020 [ 0.877646] intel_idle: v0.4 model 0x4D [ 0.877649] intel_idle: lapic_timer_reliable_states 0xffffffff root@...alhost:/sys/devices/system/cpu/cpuidle# grep . * current_driver:intel_idle current_governor_ro:menu root@...alhost:/sys/devices/system/cpu/cpuidle# Paul. -- > > Another interesting data point -- the dying board doesn't die if > I boot 3.14's x86-64 defconfig. Nothing immediately jumps out at > me in the dying .config ; there are a few tweaks in there like > RCU_NOCB etc. that I'll have to weed out with a pseudo .config > bisect I guess.... > > I'll go get the N=1 and N=2 data for the working board next. > > Paul. > -- > > > > >> The interesting part is that a nearly identical board, but with > >> different (newer/faster) CPU and newer BIOS doesn't have the hang. > > > > Possibly an electrical bug in the earlier board. > > Maybe they worked around it by disabling a C-state in ACPI > > and didn't test upstream Linux? > > > > I'd be interested in the acpi_idle output above for both the > > new and old boards to see if they are exporting different states > > on the two boards. > > > > dmidecode isn't useful in this case. The CPUID in /proc/cpuinfo > > may be useful if the problem turns out to be associated with > > some stepping. > > > > thanks, > > -Len > > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.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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