[LTP] [PATCH V3] ltp: Add a zero latency constraint for the timer tests library
Jan Stancek
jstancek@redhat.com
Tue Dec 12 15:48:08 CET 2017
Hi,
I'm running into similar problem on "Dell Precision 5820 tower", with
Intel(R) Xeon(R) W-2133 CPU @ 3.60GHz, but I can't find any /proc /sys
knob that would help.
# uname -r
4.14.5
# cat /sys/devices/system/cpu/cpu*/cpufreq/scaling_governor
performance
performance
performance
performance
performance
performance
performance
performance
performance
performance
performance
performance
Any timer related tests are reliably failing on longer timeouts:
---
tst_test.c:934: INFO: Timeout per run is 0h 05m 00s
tst_timer_test.c:356: INFO: CLOCK_MONOTONIC resolution 1ns
tst_timer_test.c:368: INFO: prctl(PR_GET_TIMERSLACK) = 50us
tst_timer_test.c:275: INFO: poll() sleeping for 1000us 500 iterations, threshold 450.01us
tst_timer_test.c:318: INFO: min 1095us, max 1098us, median 1096us, trunc mean 1095.99us (discarded 25)
tst_timer_test.c:333: PASS: Measured times are within thresholds
tst_timer_test.c:275: INFO: poll() sleeping for 2000us 500 iterations, threshold 450.01us
tst_timer_test.c:318: INFO: min 2062us, max 2138us, median 2137us, trunc mean 2135.98us (discarded 25)
tst_timer_test.c:333: PASS: Measured times are within thresholds
tst_timer_test.c:275: INFO: poll() sleeping for 5000us 300 iterations, threshold 450.04us
tst_timer_test.c:318: INFO: min 5262us, max 5263us, median 5262us, trunc mean 5262.20us (discarded 15)
tst_timer_test.c:333: PASS: Measured times are within thresholds
tst_timer_test.c:275: INFO: poll() sleeping for 10000us 100 iterations, threshold 450.33us
tst_timer_test.c:318: INFO: min 10318us, max 10471us, median 10471us, trunc mean 10469.07us (discarded 5)
tst_timer_test.c:321: FAIL: poll() slept for too long
Time: us | Frequency
--------------------------------------------------------------------------------
10318 | +
10327 |
10336 |
10345 |
10354 |
10363 |
10372 |
10381 |
10390 |
10399 |
10408 |
10417 |
10426 |
10435 | +
10444 |
10453 |
10462 |
10471 | ********************************************************************
--------------------------------------------------------------------------------
9us | 1 sample = 0.69388 '*', 1.38776 '+', 2.77551 '-', non-zero '.'
tst_timer_test.c:275: INFO: poll() sleeping for 25000us 50 iterations, threshold 451.29us
tst_timer_test.c:318: INFO: min 26096us, max 26097us, median 26096us, trunc mean 26096.00us (discarded 2)
tst_timer_test.c:321: FAIL: poll() slept for too long
Time: us | Frequency
--------------------------------------------------------------------------------
26096 | ********************************************************************
26097 | *-
--------------------------------------------------------------------------------
1us | 1 sample = 1.38776 '*', 2.77551 '+', 5.55102 '-', non-zero '.'
tst_timer_test.c:275: INFO: poll() sleeping for 100000us 10 iterations, threshold 537.00us
tst_timer_test.c:318: INFO: min 104273us, max 104274us, median 104274us, trunc mean 104273.67us (discarded 1)
tst_timer_test.c:321: FAIL: poll() slept for too long
Time: us | Frequency
--------------------------------------------------------------------------------
104273 | *****************************
104274 | ********************************************************************
--------------------------------------------------------------------------------
1us | 1 sample = 9.71429 '*', 19.42857 '+', 38.85714 '-', non-zero '.'
tst_timer_test.c:275: INFO: poll() sleeping for 1000000us 2 iterations, threshold 4400.00us
tst_timer_test.c:318: INFO: min 1007717us, max 1011050us, median 1007717us, trunc mean 1007717.00us (discarded 1)
tst_timer_test.c:321: FAIL: poll() slept for too long
Time: us | Frequency
--------------------------------------------------------------------------------
1007717 | ********************************************************************
1007893 |
1008069 |
1008245 |
1008421 |
1008597 |
1008773 |
1008949 |
1009125 |
1009301 |
1009477 |
1009653 |
1009829 |
1010005 |
1010181 |
1010357 |
1010533 |
1010709 |
1010885 | ********************************************************************
--------------------------------------------------------------------------------
176us | 1 sample = 68.00000 '*', 136.00000 '+', 272.00000 '-', non-zero '.'
---
SCHED_OTHER or SCHED_FIFO -> FAIL
intel_idle.max_cstate=0 processor.max_cstate=1 -> FAIL
echo 1 > /sys/devices/system/cpu/intel_pstate/no_turbo -> FAIL
idle=halt -> FAIL
idle=poll -> FAIL
Only thing I found to help is to keep CPU slightly busy with
taskset -c 1 sh -c "while [ True ]; do usleep 100; done"
After that it started to PASS:
# taskset -c 1 ./poll02
tst_test.c:934: INFO: Timeout per run is 0h 05m 00s
tst_timer_test.c:356: INFO: CLOCK_MONOTONIC resolution 1ns
tst_timer_test.c:368: INFO: prctl(PR_GET_TIMERSLACK) = 50us
tst_timer_test.c:275: INFO: poll() sleeping for 1000us 500 iterations, threshold 450.01us
tst_timer_test.c:318: INFO: min 1004us, max 1325us, median 1072us, trunc mean 1149.29us (discarded 25)
tst_timer_test.c:333: PASS: Measured times are within thresholds
tst_timer_test.c:275: INFO: poll() sleeping for 2000us 500 iterations, threshold 450.01us
tst_timer_test.c:318: INFO: min 2007us, max 2326us, median 2075us, trunc mean 2158.64us (discarded 25)
tst_timer_test.c:333: PASS: Measured times are within thresholds
tst_timer_test.c:275: INFO: poll() sleeping for 5000us 300 iterations, threshold 450.04us
tst_timer_test.c:318: INFO: min 5006us, max 5345us, median 5074us, trunc mean 5146.84us (discarded 15)
tst_timer_test.c:333: PASS: Measured times are within thresholds
tst_timer_test.c:275: INFO: poll() sleeping for 10000us 100 iterations, threshold 450.33us
tst_timer_test.c:318: INFO: min 10004us, max 10364us, median 10075us, trunc mean 10128.61us (discarded 5)
tst_timer_test.c:333: PASS: Measured times are within thresholds
tst_timer_test.c:275: INFO: poll() sleeping for 25000us 50 iterations, threshold 451.29us
tst_timer_test.c:318: INFO: min 25006us, max 25359us, median 25072us, trunc mean 25137.48us (discarded 2)
tst_timer_test.c:333: PASS: Measured times are within thresholds
tst_timer_test.c:275: INFO: poll() sleeping for 100000us 10 iterations, threshold 537.00us
tst_timer_test.c:318: INFO: min 100010us, max 100372us, median 100125us, trunc mean 100167.78us (discarded 1)
tst_timer_test.c:333: PASS: Measured times are within thresholds
tst_timer_test.c:275: INFO: poll() sleeping for 1000000us 2 iterations, threshold 4400.00us
tst_timer_test.c:318: INFO: min 1000843us, max 1000920us, median 1000843us, trunc mean 1000843.00us (discarded 1)
tst_timer_test.c:333: PASS: Measured times are within thresholds
Summary:
passed 7
failed 0
skipped 0
warnings 0
Any ideas?
Regards,
Jan
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