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Date: Fri, 23 Aug 2013 10:53:02 +0200
From: Martin Mokrejs <mmokrejs@...d.natur.cuni.cz>
To: Theodore Tso <tytso@....edu>, Thomas Gleixner <tglx@...utronix.de>,
mingo@...hat.com, peterz@...radead.org
CC: LKML <linux-kernel@...r.kernel.org>
Subject: [sched_delayed] sched: RT throttling activated
Hi,
I tried to figure out what this message really means. I came to
https://rt.wiki.kernel.org/index.php/Frequently_Asked_Questions
but I am still lost. I lack in the FAQ some user-related information.
The first paragraph is still unclear to me. I have a i7-2640M based
laptop, hyperthreading is enabled by BIOS but I shut down the two
emulated cores by (no BIOS option to disable HT):
echo 0 > /sys/devices/system/cpu/cpu2/online
echo 0 > /sys/devices/system/cpu/cpu3/online
At least I hope I shutdown those emulated ones. i7z claims I did the
right thing and IntelPerformanceCounterMonitorV2.5.1/pcm.x application
says the same:
EXEC : instructions per nominal CPU cycle
IPC : instructions per CPU cycle
FREQ : relation to nominal CPU frequency='unhalted clock ticks'/'invariant timer ticks' (includes Intel Turbo Boost)
AFREQ : relation to nominal CPU frequency while in active state (not in power-saving C state)='unhalted clock ticks'/'invariant timer ticks while in C0-state' (includes Intel Turbo Boost)
L3MISS: L3 cache misses
L2MISS: L2 cache misses (including other core's L2 cache *hits*)
L3HIT : L3 cache hit ratio (0.00-1.00)
L2HIT : L2 cache hit ratio (0.00-1.00)
L3CLK : ratio of CPU cycles lost due to L3 cache misses (0.00-1.00), in some cases could be >1.0 due to a higher memory latency
L2CLK : ratio of CPU cycles lost due to missing L2 cache but still hitting L3 cache (0.00-1.00)
READ : bytes read from memory controller (in GBytes)
WRITE : bytes written to memory controller (in GBytes)
TEMP : Temperature reading in 1 degree Celsius relative to the TjMax temperature (thermal headroom): 0 corresponds to the max temperature
Core (SKT) | EXEC | IPC | FREQ | AFREQ | L3MISS | L2MISS | L3HIT | L2HIT | L3CLK | L2CLK | READ | WRITE | TEMP
0 0 1.78 1.51 1.18 1.18 1595 K 3363 K 0.53 0.00 0.09 0.02 N/A N/A 23
1 0 1.21 1.03 1.18 1.18 9359 K 13 M 0.31 0.00 0.51 0.04 N/A N/A 24
-------------------------------------------------------------------------------------------------------------------
SKT 0 1.50 1.27 1.18 1.18 10 M 16 M 0.35 0.00 0.30 0.03 1.32 0.37 24
-------------------------------------------------------------------------------------------------------------------
TOTAL * 1.50 1.27 1.18 1.18 10 M 16 M 0.35 0.00 0.30 0.03 1.32 0.37 N/A
Instructions retired: 8368 M ; Active cycles: 6594 M ; Time (TSC): 2797 Mticks ; C0 (active,non-halted) core residency: 100.00 %
C1 core residency: 0.00 %; C3 core residency: 0.00 %; C6 core residency: 0.00 %; C7 core residency: 0.00 %
C2 package residency: 0.00 %; C3 package residency: 0.00 %; C6 package residency: 0.00 %; C7 package residency: 0.00 %
PHYSICAL CORE IPC : 1.27 => corresponds to 31.73 % utilization for cores in active state
Instructions per nominal CPU cycle: 1.50 => corresponds to 37.40 % core utilization over time interval
----------------------------------------------------------------------------------------------
----------------------------------------------------------------------------------------------
SKT 0 package consumed 28.18 Joules
----------------------------------------------------------------------------------------------
TOTAL: 28.18 Joules
Why do I get the message at all? I have in 3.10.9 kernel:
...
CONFIG_IOSCHED_DEADLINE=y
CONFIG_DEFAULT_IOSCHED="deadline"
...
CONFIG_NR_CPUS=4
...
# CONFIG_PREEMPT_RCU is not set
CONFIG_PREEMPT_NONE=y
# CONFIG_PREEMPT_VOLUNTARY is not set
# CONFIG_PREEMPT is not set
...
# CONFIG_SCHED_MC is not set
CONFIG_SCHED_HRTICK=y
I fear this is about CPU being overloaded (both cores loaded
by user processes), by why do I get the message at all?
Cpu speed from cpuinfo 2796.00Mhz
cpuinfo might be wrong if cpufreq is enabled. To guess correctly try estimating via tsc
Linux's inbuilt cpu_khz code emulated now
True Frequency (without accounting Turbo) 2796 MHz
CPU Multiplier 28x || Bus clock frequency (BCLK) 99.86 MHz
Socket [0] - [physical cores=2, logical cores=2, max online cores ever=2]
TURBO ENABLED on 2 Cores, Hyper Threading OFF
Max Frequency without considering Turbo 2895.86 MHz (99.86 x [29])
Max TURBO Multiplier (if Enabled) with 1/2/3/4 Cores is 35x/33x/33x/33x
Real Current Frequency 3295.29 MHz [99.86 x 33.00] (Max of below)
Core [core-id] :Actual Freq (Mult.) C0% Halt(C1)% C3 % C6 % C7 % Temp
Core 1 [0]: 3295.28 (33.00x) 100 0 0 0 0 76
Core 2 [1]: 3295.29 (33.00x) 100 0 0 0 0 76
Would you please clarify what the "[sched_delayed] sched: RT throttling activated"
really means? Is that because there is some RT-requiring application on my system?
I don't know of any (or don't care about real-time responsiveness except that ALSA
drivers require me to have CONFIG_SND_HRTIMER=y). Per Goggle answers could the
culprit be nfsd? Then I will recompile is as a module.
# ps -ef | grep nfs
root 920 2 0 Aug22 ? 00:00:00 [nfsiod]
#
Thank you,
Martin
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