RE: [PATCH 0/4] cpuidle: teo: Fix issues related to disabled idle states

Doug Smythies
2019-10-18T07:21:36Z

On 2019.10.10 Rafael J. Wysocki wrote:

> There are a few issues related to the handling of disabled idle states in the
> TEO (Timer-Events-Oriented) cpuidle governor which are addressed by this
> series.
>
> The application of the entire series is exactly equivalent to the testing patch
> at https://lore.kernel.org/lkml/3490479.2dnHFFeJIp@kreacher/ , but IMO it is
> cleaner to split the changes into smaller patches which also allows them to
> be explained more accurately.

Hi,

I have re-tested and continued testing using this 4 patch set.

Summary: So far, everything is fine.

Some, but not all, detail:

Reference kernel: 5.4-rc2 "stock"
Test kernel: 5.4-rc2 + this 4 patch set "rjw-4"

Test 1: Where I simply coded, to automate, my best use
case example:

This is an idle state 4 disabled test.
The max entries column is entries and exits for
idle state 0 over the test sample interval
(15 seconds in this case).

stock kernel:

idle-doug01 : begin ...

Per CPU PASS/FAIL : Totals: fail rate: max entries:
0 1 2 3 4 5 6 7 : : (percent): :
. . F . . . F . : 8 : 25.0000 : 69939
. . F . . . F . : 16 : 25.0000 : 69938
. . F . . . F . : 24 : 25.0000 : 70126
...
. . . . . . F F : 1928 : 30.8610 : 66530
. . . . . . F F : 1936 : 30.8368 : 68451
. . . . . . F F : 1944 : 30.8128 : 68643
. . . . . . F F : 1952 : 30.7889 : 68645
. . . . . . F F : 1960 : 30.7653 : 68152
. . . . . . F F : 1968 : 30.7419 : 67145
. . . . . . F F : 1976 : 30.7186 : 67349
. . . . . . F F : 1984 : 30.6956 : 68481
. . . . . . F F : 1992 : 30.6727 : 67394
. . . . . . F F : 2000 : 30.6500 : 68645
^C --- SIGINT (^C) detected. Terminate gracefully, saving the sample data...
. . . . . . F F : 2008 : 30.6275 : 29010

Summary: Total Tests: 2008 : Total Fails: 615 : Fail rate (percent): 30.6275 : Per CPU:
CPU00: 0, CPU01: 0, CPU02: 12, CPU03: 0, CPU04: 152, CPU05: 43, CPU06: 197, CPU07: 211,

idle-doug01 : end ...

rjw-4 kernel:

idle-doug01 : begin ...

Per CPU PASS/FAIL : Totals: fail rate: max entries:
0 1 2 3 4 5 6 7 : : (percent): :
. . . . . . . . : 8 : 0.0000 : 3
. . . . . . . . : 16 : 0.0000 : 7
. . . . . . . . : 24 : 0.0000 : 10
. . . . . . . . : 32 : 0.0000 : 10
. . . . . . . . : 40 : 0.0000 : 23
. . . . . . . . : 48 : 0.0000 : 23
. . . . . . . . : 56 : 0.0000 : 1
. . . . . . . . : 64 : 0.0000 : 1
. . . . . . . . : 72 : 0.0000 : 0
. . . . . . . . : 80 : 0.0000 : 0
. . . . . . . . : 88 : 0.0000 : 1
. . . . . . . . : 96 : 0.0000 : 1
. . . . . . . . : 104 : 0.0000 : 0
. . . . . . . . : 112 : 0.0000 : 0
. . . . . . . . : 120 : 0.0000 : 1
. . . . . . . . : 128 : 0.0000 : 2
. . . . . . . . : 136 : 0.0000 : 2
. . . . . . . . : 144 : 0.0000 : 3
. . . . . . . . : 152 : 0.0000 : 3
. . . . . . . . : 160 : 0.0000 : 4
. . . . . . . . : 168 : 0.0000 : 4
. . . . . . . . : 176 : 0.0000 : 6
. . . . . . . . : 184 : 0.0000 : 3
. . . . . . . . : 192 : 0.0000 : 4
...
. . . . . . . . : 11480 : 0.0000 : 5
. . . . . . . . : 11488 : 0.0000 : 4
. . . . . . . . : 11496 : 0.0000 : 6
. . . . . . . . : 11504 : 0.0000 : 8
. . . . . . . . : 11512 : 0.0000 : 5
. . . . . . . . : 11520 : 0.0000 : 4
. . . . . . . . : 11528 : 0.0000 : 4
. . . . . . . . : 11536 : 0.0000 : 3
. . . . . . . . : 11544 : 0.0000 : 2
. . . . . . . . : 11552 : 0.0000 : 5
. . . . . . . . : 11560 : 0.0000 : 3
. . . . . . . . : 11568 : 0.0000 : 3
^C --- SIGINT (^C) detected. Terminate gracefully, saving the sample data...
. . . . . . . . : 11576 : 0.0000 : 1

Summary: Total Tests: 11576 : Total Fails: 0 : Fail rate (percent): 0.0000 : Per CPU:
CPU00: 0, CPU01: 0, CPU02: 0, CPU03: 0, CPU04: 0, CPU05: 0, CPU06: 0, CPU07: 0,

idle-doug01 : end ...

Test 2: Have a look at all idle state enabled/disabled combinations.
This test is not very good, and only looks at processor package power.
Particularly for idle state 1, see Note 1 below.
But it's better than nothing.

stock kernel:

idle-disable-enable : begin ...

Idle State: Per test PASS/FAIL : Power (Watts) :
4 3 2 1 0 : : Expected : Max diff :
0 0 0 0 0 : PASS PASS PASS PASS PASS PASS PASS PASS : 3.7 : 0.2
0 0 0 0 1 : PASS PASS PASS PASS PASS PASS PASS PASS : 3.7 : 0.2
0 0 0 1 0 : PASS PASS PASS PASS PASS PASS PASS PASS : 3.7 : 0.2
0 0 0 1 1 : PASS PASS PASS PASS PASS PASS PASS PASS : 3.7 : 0.2
0 0 1 0 0 : PASS PASS PASS PASS PASS PASS PASS PASS : 3.7 : 0.2
0 0 1 0 1 : PASS PASS PASS PASS PASS PASS PASS PASS : 3.7 : 0.2
0 0 1 1 0 : PASS PASS PASS PASS PASS PASS PASS PASS : 3.7 : 0.2
0 0 1 1 1 : PASS PASS PASS PASS PASS PASS PASS PASS : 3.7 : 0.2
0 1 0 0 0 : PASS PASS PASS PASS PASS PASS PASS PASS : 3.7 : 0.2
0 1 0 0 1 : PASS PASS PASS PASS PASS PASS PASS PASS : 3.7 : 0.2
0 1 0 1 0 : PASS PASS PASS PASS PASS PASS PASS PASS : 3.7 : 0.2
0 1 0 1 1 : PASS PASS PASS PASS PASS PASS PASS PASS : 3.7 : 0.2
0 1 1 0 0 : PASS PASS PASS PASS PASS PASS PASS PASS : 3.7 : 0.2
0 1 1 0 1 : PASS PASS PASS PASS PASS PASS PASS PASS : 3.7 : 0.2
0 1 1 1 0 : PASS PASS PASS PASS PASS PASS PASS PASS : 3.7 : 0.2
0 1 1 1 1 : PASS PASS PASS PASS PASS PASS PASS PASS : 3.7 : 0.2
1 0 0 0 0 : FAIL FAIL FAIL FAIL FAIL FAIL FAIL FAIL : 4.9 : 17.0
1 0 0 0 1 : FAIL PASS PASS PASS PASS PASS PASS PASS : 4.9 : 1.6
1 0 0 1 0 : PASS PASS PASS PASS PASS PASS PASS PASS : 4.9 : 0.8
1 0 0 1 1 : PASS PASS PASS PASS PASS PASS PASS PASS : 4.9 : 0.8
1 0 1 0 0 : PASS FAIL FAIL FAIL FAIL FAIL FAIL FAIL : 4.9 : 19.9
1 0 1 0 1 : PASS PASS PASS PASS PASS PASS PASS PASS : 4.9 : 0.9
1 0 1 1 0 : PASS PASS PASS PASS PASS PASS PASS PASS : 4.9 : 0.8
1 0 1 1 1 : PASS PASS PASS PASS PASS PASS PASS PASS : 4.9 : 0.8
1 1 0 0 0 : PASS PASS PASS PASS PASS PASS PASS PASS : 8.7 : 0.7
1 1 0 0 1 : PASS PASS PASS PASS PASS PASS PASS PASS : 8.7 : 0.7
1 1 0 1 0 : PASS PASS PASS PASS PASS PASS PASS PASS : 8.7 : 0.7
1 1 0 1 1 : PASS PASS PASS PASS PASS PASS PASS PASS : 8.7 : 0.7
1 1 1 0 0 : FAIL PASS PASS PASS PASS PASS PASS PASS : 9.6 : 2.5
1 1 1 0 1 : FAIL PASS PASS PASS PASS PASS PASS PASS : 9.6 : 11.3 <<< Note 1.
1 1 1 1 0 : PASS PASS PASS PASS PASS PASS PASS PASS : 52.0 : 1.0
1 1 1 1 1 : PASS PASS PASS PASS PASS PASS PASS PASS : 52.0 : 1.4

idle-disable-enable : end ...

rjw-4 kernel:

Note: Reduced to 3 tests per combination. 8 seconds per sample.

idle-disable-enable : begin ...

Idle State: Per test PASS/FAIL : Power (Watts) :
4 3 2 1 0 : : Expected : Max diff :
0 0 0 0 0 : PASS PASS PASS : 3.7 : 0.2
0 0 0 0 1 : PASS PASS PASS : 3.7 : 0.2
0 0 0 1 0 : PASS PASS PASS : 3.7 : 0.2
0 0 0 1 1 : PASS PASS PASS : 3.7 : 0.2
0 0 1 0 0 : PASS PASS PASS : 3.7 : 0.3
0 0 1 0 1 : PASS PASS PASS : 3.7 : 0.2
0 0 1 1 0 : PASS PASS PASS : 3.7 : 0.2
0 0 1 1 1 : PASS PASS PASS : 3.7 : 0.3
0 1 0 0 0 : PASS PASS PASS : 3.7 : 0.2
0 1 0 0 1 : PASS PASS PASS : 3.7 : 0.3
0 1 0 1 0 : PASS PASS PASS : 3.7 : 0.3
0 1 0 1 1 : PASS PASS PASS : 3.7 : 0.2
0 1 1 0 0 : PASS PASS PASS : 3.7 : 0.2
0 1 1 0 1 : PASS PASS PASS : 3.7 : 0.2
0 1 1 1 0 : PASS PASS PASS : 3.7 : 0.3
0 1 1 1 1 : PASS PASS PASS : 3.7 : 0.3
1 0 0 0 0 : PASS PASS PASS : 4.9 : 0.8
1 0 0 0 1 : PASS PASS PASS : 4.9 : 0.8
1 0 0 1 0 : PASS PASS PASS : 4.9 : 0.8
1 0 0 1 1 : PASS PASS PASS : 4.9 : 0.8
1 0 1 0 0 : PASS PASS PASS : 4.9 : 0.8
1 0 1 0 1 : PASS PASS PASS : 4.9 : 0.8
1 0 1 1 0 : PASS PASS PASS : 4.9 : 0.8
1 0 1 1 1 : PASS PASS PASS : 4.9 : 0.8
1 1 0 0 0 : PASS PASS PASS : 8.7 : 0.8
1 1 0 0 1 : PASS PASS PASS : 8.7 : 0.8
1 1 0 1 0 : PASS PASS PASS : 8.7 : 0.9
1 1 0 1 1 : PASS PASS PASS : 8.7 : 0.9
1 1 1 0 0 : PASS PASS PASS : 9.6 : 1.7
1 1 1 0 1 : FAIL PASS PASS : 9.6 : 2.1 <<< Note 1.
1 1 1 1 0 : PASS PASS PASS : 52.0 : 0.5
1 1 1 1 1 : PASS PASS PASS : 52.0 : 1.0

idle-disable-enable : end ...

Note 1:
The processor package power used in idle state 1 is
a strong function of the current p-state setting:
p-state 16 (lowest): 8.8 watts
p-state 38 (highest): 21.9 watts
When the system load goes to idle during this test,
it can take on the order of 10s of seconds for the
intel-pstate driver to request low p-states for
all CPUs. If there is an issue here, it is a subject
for another day.

... Doug