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From: Patrick Pannuto on 24 Jun 2010 13:00
Andi Kleen wrote:
> Patrick Pannuto <ppannuto(a)codeaurora.org> writes:
>
> Overall it seems like a good improvement.
>
>> +
>> +static inline void usleep(unsigned long usecs)
>> +{
>> + usleep_range(usecs, usecs);
>> +}
>> +
>> +static inline unsigned long usleep_interruptible(unsigned long usecs)
>
> Is the interruptible case even needed? I assume most drivers won't
> bother with that and not being interruptible for a few usecs is not a
> big issue.

Honestly, I don't think so, but I was mirroring the msleep API when
I wrote it so I included it for completeness. I can't think of a use
case where it is necessary / useful. I will remove it unless anyone
can think of an application for it?

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From: Pavel Machek on 26 Jun 2010 17:50
Hi!

> > Yes, this test was leftover from a different project that involved refactoring
> > timers, so it was available and easy. My guess for the reduction in number of
> > wakeups is that the processor is able to do other work during the 100us it was
> > previously busy-waiting, and thus had to wake up less often.
>
> As I said in the prior email the udelay()'s don't preclude other types
> of work since you can get preempted.

Yes, you can get preempted, but you'll still spin in the tight loop
counting...

So it does not preclude other task, but then you'll spin
unneccessarily.
Pavel
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From: Patrick Pannuto on 28 Jun 2010 14:10
>
> You could test residency in specific power states .. Since you want to
> test if your reducing power consumption .. However, I'd replace a ton
> more of these udelay()'s , I don't think you'll get a decent results
> with out that.
>

Ok.

>
> The busy waits your replacing are small in length on average .. If you
> have timers that trigger in small intervals then your not going to
> increase residency in any _lower_ power states .. It's possible that you
> could increase residency in the top level power state, but it seem like
> it would be really marginal .. You need to show that udelay()'s have an
> outside of noise impact on something ..
>

Ok.

>
> I think you need to do some more research on what your actually doing to
> the system. From what your showing us one could make a lot of different
> arguments as to what this change will actually do. You really need some
> sort of test that doesn't leave a lot of room for argument.
>

Well here we go then.

First, I would note that IMO is both telling and remarkable that the
following (almost) worked and allowed the system to boot successfully:

(a little long since you can cut off half of it and just get a list of
affected / candidate files, the following is a glorified sed that
replaces all instances of udelay with usleep for udelay's >= 50us)

git grep 'udelay([[:digit:]]\+)' |
perl -F"[\(\)]" -anl -e 'print if $F[1] >= 50' |
cut -d: -f1 |
uniq |
grep -v staging |
xargs perl -i -wlpe
's/udelay/usleep/ if m/udelay\((\d+)\)/g && $1 >= 50'

The usb driver and one power routine that was in a critical section had
to be reverted; everything else ran successfully.


*** MEASUREMENT TECHNIQUE ***

/proc/msm_pm_stats will dump information on residency in power states as
the system is running; dumps were taken 15s, 30s, 60s, 120s, 180s, and
240s from boot. 10 trials were performed for each build. A trial was run
replacing udelay >1000, >500, >100, >=100, >=50.

origin: 0 changes (0 total)
over1000: 106 changes (106 total)
over500: 193 changes (299 total)
over100: 302 changes (601 total)
equal100: 423 changes (1024 total)
equal50: 220 changes (1244 total)

Now, a concern is obviously that these changes hit drivers that are not
used in this system, or that many will be hit only once in boot /
initialization / etc; this shows plainly in the results and will be
addressed.


*** RESULTS ***

Complete results are attached (please forgive the ugly stats.py, it
evolved; it's functional for the task at hand, but certainly not pretty).

--> Long results also at end of email

From the final results, after 240s:

TIME STATE #TIMES CALLED TIME IN STATE | DELTA FROM ORG

////////////////////////////////////////////////////////////////////////////////
=== origin (10 samples) =================================== RUNTIME: 241.535 ===
240 idle-spin -- 2.3 1.45001e-05
240 not-idle -- 88368.2 67.8311703321
240 idle-request -- 88367.2 23337.6322655
240 idle-wfi -- 88364.9 172.296383696
=== over1000 (10 samples) ====== (delta: -0.00999999998604) RUNTIME: 241.525 ===
240 idle-spin -- 3.1 1.91666e-05 | 4.6665e-06
240 not-idle -- 88723.9 65.6361809172 | -2.1949894149
240 idle-request -- 88722.9 23311.9855603 | -25.6467051707
240 idle-wfi -- 88719.8 174.493487111 | 2.1971034149
=== over500 (10 samples) ======== (delta: -0.0339999999851) RUNTIME: 241.501 ===
240 idle-spin -- 2.3 1.88334e-05 | 4.3333e-06
240 not-idle -- 88636.3 67.0242803241 | -0.806890008
240 idle-request -- 88635.3 23280.1632631 | -57.469002442
240 idle-wfi -- 88633.0 173.077055869 | 0.7806721723
=== over100 (10 samples) ======== (delta: -0.0539999999921) RUNTIME: 241.481 ===
240 idle-spin -- 0.9 6.6666e-06 | -7.8335e-06
240 not-idle -- 88599.0 67.190273164 | -0.6408971681
240 idle-request -- 88597.9 23253.4797828 | -84.1524827638
240 idle-wfi -- 88597.0 172.884529866 | 0.5881461694
=== equal100 (10 samples) ================== (delta: -0.025) RUNTIME: 241.51 ===
240 idle-spin -- 1.4 9.5002e-06 | -4.9999e-06
240 not-idle -- 88685.9 66.5067348407 | -1.3244354914
240 idle-request -- 88684.9 23294.4341497 | -43.1981158192
240 idle-wfi -- 88683.5 173.60379269 | 1.3074089936
=== equal50 (10 samples) ======== (delta: -0.0289999999804) RUNTIME: 241.506 ===
240 idle-spin -- 2.0 9.6664e-06 | -4.8337e-06
240 not-idle -- 88537.4 65.8619214556 | -1.9692488765
240 idle-request -- 88536.4 22979.3665406 | -358.265724952
240 idle-wfi -- 88534.4 174.247270576 | 1.9508868794


There appears to be very little change outside of noise from origin through
equal100, however, once equal50 is reached, there is a noticeable change.
Further investigation revealed that before equal100, none of the changes
could be guaranteed to hit the testing target (which, if nothing else,
provides a nice baseline for noise). The equal100 test included 3 changes
that could positively be sure to hit target and the equal50 test another
4 changes. The equal50 test was the only test that seems to conclusively
show immediate benefit, but it *does* show benefit.

(here "positively sure" are arch-specific drivers that changed, easy to
search for; it's likely that more did hit the target along the way)


*** CONCLUSIONS ***

I submit that the concept of usleep introduces no harm and does have the
potential for benefit. I further submit that as processors get faster, the
benefit from a usleep versus a udelay will only improve. Finally, I would note
that the success of the "sed" implies to me that many users of udelay would
prefer the semantics of a usleep call; it is simply unavailable and msleep is
simply too imprecise for callers to use, which is in and of itself a case
for a usleep API.

I invite comments, questions, etc, and am happy to run more tests; however,
I would like to request that if you for any reason believe this data to be
imprecise or insufficient that you please provide me with the *exact* test you
would like me to run and would like to see data from, since it does take a
fair amount of time to run these tests.

Finally, I would like to re-iterate my point that unnecessary busy-waiting,
while it *can* be pre-empted, *is* wasteful and __if it can easily be avoided,
it should be__.

-Pat


*** LONG RESULTS ***

==> Attached is pm_stats.tar.gz, it contains results as TEST_TRIALNO,
flash.sh to run tests (./flash.sh pm_stats TESTNAME) run from an Android
product directory, and stats.py to generate statistics. Forgive stats.py,
it is ugly and an abuse of python.

TIME STATE #TIMES CALLED TIME IN STATE | DELTA FROM ORG

////////////////////////////////////////////////////////////////////////////////
=== origin (10 samples) ==================================== RUNTIME: 15.253 ===
15 idle-spin -- 1.1 4.8332e-06
15 not-idle -- 59265.1 9.3842608833
15 idle-request -- 59262.2 21892.7762788
15 idle-wfi -- 59261.1 4.4754141812
=== over1000 (10 samples) ======== (delta: -0.00299999999115) RUNTIME: 15.25 ===
15 idle-spin -- 0.7 3.6666e-06 | -1.1666e-06
15 not-idle -- 59243.9 9.3891611869 | 0.0049003036
15 idle-request -- 59237.1 21897.8631197 | 5.0868408908
15 idle-wfi -- 59236.4 4.4665700454 | -0.0088441358
=== over500 (10 samples) ======== (delta: -0.00899999999674) RUNTIME: 15.244 ===
15 idle-spin -- 0.5 2.8334e-06 | -1.9998e-06
15 not-idle -- 59267.2 9.3819648583 | -0.002296025
15 idle-request -- 59263.2 21894.5342115 | 1.75793271321
15 idle-wfi -- 59262.7 4.4662633725 | -0.0091508087
=== over100 (10 samples) ======== (delta: -0.00200000000186) RUNTIME: 15.251 ===
15 idle-spin -- 0.1 1.1666e-06 | -3.6666e-06
15 not-idle -- 59222.3 9.4040358354 | 0.0197749521
15 idle-request -- 59213.6 21893.1330305 | 0.356751724303
15 idle-wfi -- 59213.5 4.4462678975 | -0.0291462837
=== equal100 (10 samples) ======= (delta: -0.00599999999395) RUNTIME: 15.247 ===
15 idle-spin -- 0.1 5e-07 | -4.3332e-06
15 not-idle -- 59311.6 9.392722999 | 0.0084621157
15 idle-request -- 59306.0 21900.290705 | 7.5144261487
15 idle-wfi -- 59305.9 4.4606828991 | -0.0147312821
=== equal50 (10 samples) ====================== (delta: 0.0) RUNTIME: 15.253 ===
15 idle-spin -- 0.6 1.8333e-06 | -2.9999e-06
15 not-idle -- 59267.0 9.4182486803 | 0.033987797
15 idle-request -- 59261.4 21613.5706545 | -279.205624353
15 idle-wfi -- 59260.8 4.4418992194 | -0.0335149618
////////////////////////////////////////////////////////////////////////////////
=== origin (10 samples) ==================================== RUNTIME: 30.494 ===
30 idle-spin -- 1.2 5.1666e-06
30 not-idle -- 69462.2 21.80567204
30 idle-request -- 69462.2 22568.1921778
30 idle-wfi -- 69461.0 6.8173021886
=== over1000 (10 samples) ======= (delta: -0.00100000001257) RUNTIME: 30.493 ===
30 idle-spin -- 1.1 6.3332e-06 | 1.1666e-06
30 not-idle -- 69436.0 21.7969753263 | -0.0086967137
30 idle-request -- 69436.0 22564.1587592 | -4.0334186002
30 idle-wfi -- 69434.9 6.8029330699 | -0.0143691187
=== over500 (10 samples) ======== (delta: -0.00700000001816) RUNTIME: 30.487 ===
30 idle-spin -- 0.6 3.1667e-06 | -1.9999e-06
30 not-idle -- 69474.6 21.7808043443 | -0.0248676957
30 idle-request -- 69474.6 22564.0631218 | -4.1290559666
30 idle-wfi -- 69474.0 6.7958443852 | -0.0214578034
=== over100 (10 samples) ========= (delta: 0.00099999998929) RUNTIME: 30.495 ===
30 idle-spin -- 0.2 1.6666e-06 | -3.5e-06
30 not-idle -- 69379.1 21.8042313156 | -0.0014407244
30 idle-request -- 69379.1 22551.153217 | -17.0389607525
30 idle-wfi -- 69378.9 6.7590274145 | -0.0582747741
=== equal100 (10 samples) ======= (delta: -0.00300000001443) RUNTIME: 30.491 ===
30 idle-spin -- 0.2 1e-06 | -4.1666e-06
30 not-idle -- 69455.7 21.8058526573 | 0.0001806173
30 idle-request -- 69455.7 22570.70418 | 2.51200219339
30 idle-wfi -- 69455.5 6.7603640729 | -0.0569381157
=== equal50 (10 samples) ======== (delta: -0.00100000002421) RUNTIME: 30.493 ===
30 idle-spin -- 0.9 3.8332e-06 | -1.3334e-06
30 not-idle -- 69449.7 21.8319953111 | 0.0263232711
30 idle-request -- 69449.7 22271.8053346 | -296.386843177
30 idle-wfi -- 69448.8 6.7478177546 | -0.069484434
////////////////////////////////////////////////////////////////////////////////
=== origin (10 samples) ===================================== RUNTIME: 60.78 ===
60 idle-spin -- 1.9 1.16667e-05
60 not-idle -- 79366.8 49.3036608463
60 idle-request -- 79366.3 22907.1705373
60 idle-wfi -- 79364.4 9.0110567161
=== over1000 (10 samples) ========= (delta: 0.0139999999898) RUNTIME: 60.794 ===
60 idle-spin -- 2.0 1.36668e-05 | 2.0001e-06
60 not-idle -- 79493.9 49.8914426181 | 0.5877817718
60 idle-request -- 79491.4 22894.3020036 | -12.8685336944
60 idle-wfi -- 79489.4 9.0156314459 | 0.0045747298
=== over500 (10 samples) ========== (delta: -0.010999999987) RUNTIME: 60.769 ===
60 idle-spin -- 1.5 1.14999e-05 | -1.668e-07
60 not-idle -- 79513.5 49.7980203079 | 0.4943594616
60 idle-request -- 79512.6 22869.995713 | -37.1748243636
60 idle-wfi -- 79511.1 9.0027399223 | -0.0083167938
=== over100 (10 samples) ========= (delta: -0.0229999999865) RUNTIME: 60.757 ===
60 idle-spin -- 0.8 6.3332e-06 | -5.3335e-06
60 not-idle -- 79399.4 49.8599212971 | 0.5562604508
60 idle-request -- 79396.8 22849.5517755 | -57.6187617949
60 idle-wfi -- 79396.0 8.9517647664 | -0.0592919497
=== equal100 (10 samples) ======= (delta: -0.00699999999488) RUNTIME: 60.773 ===
60 idle-spin -- 1.0 6.1667e-06 | -5.5e-06
60 not-idle -- 79508.7 49.7887594666 | 0.4850986203
60 idle-request -- 79506.3 22878.2886511 | -28.8818862207
60 idle-wfi -- 79505.3 8.9810057637 | -0.0300509524
=== equal50 (10 samples) ======== (delta: -0.00799999999581) RUNTIME: 60.772 ===
60 idle-spin -- 1.4 5.9998e-06 | -5.6669e-06
60 not-idle -- 79401.8 49.7245356251 | 0.4208747788
60 idle-request -- 79401.8 22589.3334706 | -317.837066708
60 idle-wfi -- 79400.4 8.9224572725 | -0.0885994436
////////////////////////////////////////////////////////////////////////////////
=== origin (10 samples) =================================== RUNTIME: 121.018 ===
120 idle-spin -- 2.3 1.45001e-05
120 not-idle -- 84534.3 65.4829273526
120 idle-request -- 84533.2 23073.5171825
120 idle-wfi -- 84530.9 54.1388846978
=== over1000 (10 samples) ======== (delta: 0.0149999999907) RUNTIME: 121.033 ===
120 idle-spin -- 2.9 1.76667e-05 | 3.1666e-06
120 not-idle -- 84899.7 62.9539904388 | -2.5289369138
120 idle-request -- 84898.6 23058.6542567 | -14.8629258454
120 idle-wfi -- 84895.7 56.6840665995 | 2.5451819017
=== over500 (10 samples) ======= (delta: -0.00999999999767) RUNTIME: 121.008 ===
120 idle-spin -- 2.1 1.61667e-05 | 1.6666e-06
120 not-idle -- 84810.4 64.5704918038 | -0.9124355488
120 idle-request -- 84809.3 23020.7240229 | -52.7931596084
120 idle-wfi -- 84807.2 55.0429809068 | 0.904096209
=== over100 (10 samples) ======== (delta: -0.0209999999963) RUNTIME: 120.997 ===
120 idle-spin -- 0.9 6.6666e-06 | -7.8335e-06
120 not-idle -- 84773.7 64.6287104755 | -0.8542168771
120 idle-request -- 84772.7 23002.4330668 | -71.0841157664
120 idle-wfi -- 84771.8 54.9635557389 | 0.8246710411
=== equal100 (10 samples) ======= (delta: 0.00600000000559) RUNTIME: 121.024 ===
120 idle-spin -- 1.4 9.5002e-06 | -4.9999e-06
120 not-idle -- 84843.8 63.8751059888 | -1.6078213638
120 idle-request -- 84842.8 23042.7777274 | -30.7394551461
120 idle-wfi -- 84841.4 55.7466510555 | 1.6077663577
=== equal50 (10 samples) ======= (delta: -0.00099999998929) RUNTIME: 121.017 ===
120 idle-spin -- 2.0 9.6664e-06 | -4.8337e-06
120 not-idle -- 84767.4 63.0424664541 | -2.4404608985
120 idle-request -- 84766.4 22740.2895937 | -333.227588835
120 idle-wfi -- 84764.4 56.5740535877 | 2.4351688899
////////////////////////////////////////////////////////////////////////////////
=== origin (10 samples) =================================== RUNTIME: 181.273 ===
180 idle-spin -- 2.3 1.45001e-05
180 not-idle -- 86458.1 66.7356990125
180 idle-request -- 86457.1 23202.3433604
180 idle-wfi -- 86454.8 113.126771849
=== over1000 (10 samples) ========= (delta: 0.010999999987) RUNTIME: 181.284 ===
180 idle-spin -- 3.0 1.83333e-05 | 3.8332e-06
180 not-idle -- 86831.3 64.5482361081 | -2.1874629044
180 idle-request -- 86830.3 23181.3150713 | -21.028289176
180 idle-wfi -- 86827.3 115.331773087 | 2.2050012376
=== over500 (10 samples) ======== (delta: -0.0250000000117) RUNTIME: 181.248 ===
180 idle-spin -- 2.2 1.68334e-05 | 2.3333e-06
180 not-idle -- 86733.7 65.9390319914 | -0.7966670211
180 idle-request -- 86732.7 23151.5750952 | -50.7682652808
180 idle-wfi -- 86730.5 113.915960535 | 0.7891886856
=== over100 (10 samples) ======== (delta: -0.0339999999968) RUNTIME: 181.239 ===
180 idle-spin -- 0.9 6.6666e-06 | -7.8335e-06
180 not-idle -- 86696.8 66.0923128287 | -0.6433861838
180 idle-request -- 86695.7 23122.6406168 | -79.7027435974
180 idle-wfi -- 86694.8 113.744699867 | 0.6179280181
=== equal100 (10 samples) ======= (delta: -0.0060000000056) RUNTIME: 181.267 ===
180 idle-spin -- 1.4 9.5002e-06 | -4.9999e-06
180 not-idle -- 86765.3 65.4099056755 | -1.325793337
180 idle-request -- 86764.2 23156.7172921 | -45.6260683097
180 idle-wfi -- 86762.8 114.457775355 | 1.3310035056
=== equal50 (10 samples) ======= (delta: -0.00799999998418) RUNTIME: 181.265 ===
180 idle-spin -- 2.0 9.6664e-06 | -4.8337e-06
180 not-idle -- 86665.1 64.770143973 | -1.9655550395
180 idle-request -- 86664.1 22851.7003915 | -350.642968977
180 idle-wfi -- 86662.1 115.098642558 | 1.971870709
////////////////////////////////////////////////////////////////////////////////
=== origin (10 samples) =================================== RUNTIME: 241.535 ===
240 idle-spin -- 2.3 1.45001e-05
240 not-idle -- 88368.2 67.8311703321
240 idle-request -- 88367.2 23337.6322655
240 idle-wfi -- 88364.9 172.296383696
=== over1000 (10 samples) ====== (delta: -0.00999999998604) RUNTIME: 241.525 ===
240 idle-spin -- 3.1 1.91666e-05 | 4.6665e-06
240 not-idle -- 88723.9 65.6361809172 | -2.1949894149
240 idle-request -- 88722.9 23311.9855603 | -25.6467051707
240 idle-wfi -- 88719.8 174.493487111 | 2.1971034149
=== over500 (10 samples) ======== (delta: -0.0339999999851) RUNTIME: 241.501 ===
240 idle-spin -- 2.3 1.88334e-05 | 4.3333e-06
240 not-idle -- 88636.3 67.0242803241 | -0.806890008
240 idle-request -- 88635.3 23280.1632631 | -57.469002442
240 idle-wfi -- 88633.0 173.077055869 | 0.7806721723
=== over100 (10 samples) ======== (delta: -0.0539999999921) RUNTIME: 241.481 ===
240 idle-spin -- 0.9 6.6666e-06 | -7.8335e-06
240 not-idle -- 88599.0 67.190273164 | -0.6408971681
240 idle-request -- 88597.9 23253.4797828 | -84.1524827638
240 idle-wfi -- 88597.0 172.884529866 | 0.5881461694
=== equal100 (10 samples) ================== (delta: -0.025) RUNTIME: 241.51 ===
240 idle-spin -- 1.4 9.5002e-06 | -4.9999e-06
240 not-idle -- 88685.9 66.5067348407 | -1.3244354914
240 idle-request -- 88684.9 23294.4341497 | -43.1981158192
240 idle-wfi -- 88683.5 173.60379269 | 1.3074089936
=== equal50 (10 samples) ======== (delta: -0.0289999999804) RUNTIME: 241.506 ===
240 idle-spin -- 2.0 9.6664e-06 | -4.8337e-06
240 not-idle -- 88537.4 65.8619214556 | -1.9692488765
240 idle-request -- 88536.4 22979.3665406 | -358.265724952
240 idle-wfi -- 88534.4 174.247270576 | 1.9508868794
From: Daniel Walker on 28 Jun 2010 15:40
On Mon, 2010-06-28 at 11:03 -0700, Patrick Pannuto wrote:

> Well here we go then.

Great.


> *** RESULTS ***
>
> Complete results are attached (please forgive the ugly stats.py, it
> evolved; it's functional for the task at hand, but certainly not pretty).
>
> --> Long results also at end of email
>
> From the final results, after 240s:
>
> TIME STATE #TIMES CALLED TIME IN STATE | DELTA FROM ORG
>
> ////////////////////////////////////////////////////////////////////////////////
> === origin (10 samples) =================================== RUNTIME: 241.535 ===

What's the 10 samples here?

> 240 idle-spin -- 2.3 1.45001e-05
> 240 not-idle -- 88368.2 67.8311703321
> 240 idle-request -- 88367.2 23337.6322655
> 240 idle-wfi -- 88364.9 172.296383696

I'm going to assume you did ten in "origin" (i.e. control runs) and
averaged. However, you need to explicitly say that ..

What units is "time in state", and what interfacing does the timing? Are
these states in order from least power saving to most power savings?

> === over1000 (10 samples) ====== (delta: -0.00999999998604) RUNTIME: 241.525 ===
> 240 idle-spin -- 3.1 1.91666e-05 | 4.6665e-06
> 240 not-idle -- 88723.9 65.6361809172 | -2.1949894149
> 240 idle-request -- 88722.9 23311.9855603 | -25.6467051707
> 240 idle-wfi -- 88719.8 174.493487111 | 2.1971034149
> === over500 (10 samples) ======== (delta: -0.0339999999851) RUNTIME: 241.501 ===
> 240 idle-spin -- 2.3 1.88334e-05 | 4.3333e-06
> 240 not-idle -- 88636.3 67.0242803241 | -0.806890008
> 240 idle-request -- 88635.3 23280.1632631 | -57.469002442
> 240 idle-wfi -- 88633.0 173.077055869 | 0.7806721723
> === over100 (10 samples) ======== (delta: -0.0539999999921) RUNTIME: 241.481 ===
> 240 idle-spin -- 0.9 6.6666e-06 | -7.8335e-06
> 240 not-idle -- 88599.0 67.190273164 | -0.6408971681
> 240 idle-request -- 88597.9 23253.4797828 | -84.1524827638
> 240 idle-wfi -- 88597.0 172.884529866 | 0.5881461694
> === equal100 (10 samples) ================== (delta: -0.025) RUNTIME: 241.51 ===
> 240 idle-spin -- 1.4 9.5002e-06 | -4.9999e-06
> 240 not-idle -- 88685.9 66.5067348407 | -1.3244354914
> 240 idle-request -- 88684.9 23294.4341497 | -43.1981158192
> 240 idle-wfi -- 88683.5 173.60379269 | 1.3074089936
> === equal50 (10 samples) ======== (delta: -0.0289999999804) RUNTIME: 241.506 ===
> 240 idle-spin -- 2.0 9.6664e-06 | -4.8337e-06
> 240 not-idle -- 88537.4 65.8619214556 | -1.9692488765
> 240 idle-request -- 88536.4 22979.3665406 | -358.265724952
> 240 idle-wfi -- 88534.4 174.247270576 | 1.9508868794
>
>
> There appears to be very little change outside of noise from origin through
> equal100, however, once equal50 is reached, there is a noticeable change.

it all looks pretty noisy still, but it could be that your just
providing too much information ...

Ok, so the idle-request state had residency of 22979us (guessing units)
in equal50, and 23338us in the control. Which is %1.5 less. I would
think you want more residency rather than less right?

Replacing 50us udelays with timers will cause more timers to trigger at
a high frequency, which would cause you to be running timer code more
often rather than doing something else (maybe being in a sleep state).
So the number make some sense.

Does over100 include everything from 100 to 1000 ?

Daniel

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