[GUI] Support gui.fps_limit and reduce idle power consumption #1611

archibate · 2020-07-30T01:31:14Z

Related issue = #

Setting gui.fps_limit = None make fractal.py to be ~140 fps on CUDA!
Some tweaks in system/timer.cpp is also done for reducing CPU usage on idle (when actual FPS > our FPS limit).

JYLeeLYJ

Nice idea !
And here are two platform-specific optimization points for windows .

JYLeeLYJ · 2020-07-30T08:00:13Z

taichi/system/timer.cpp

@@ -69,6 +69,24 @@ void Time::sleep(double s) {
  Time::usleep(s * 1e6_f64);
 }


Here is a mush more accurate milliseconds level sleep implementation instead of Sleep(DWORD(us * 1e-3)) on windows .

#ifdef _WIN64 #include <Windows.h> #pragma comment(lib, "Winmm.lib") void win_sleep(DWORD ms) { if (ms == 0) Sleep(0); else { HANDLE hEvent = CreateEvent(NULL, FALSE, FALSE, NULL); timeSetEvent(ms, 1, (LPTIMECALLBACK)hEvent , 0, TIME_ONESHOT | TIME_CALLBACK_EVENT_SET); WaitForSingleObject(hEvent, INFINITE); CloseHandle(hEvent); } } #endif

Sounds cool! But is that possible to sleep for microseconds (us) on Windows?

Sounds cool! But is that possible to sleep for microseconds (us) on Windows?

It's sad truth that sleep accuracy can not be guaranteed when delay time is lower than 1ms :(
The only possible approach is to use high resolution clock to continually counting in a for loop , but it 's unable to release CPU time slice ...

Related problem : is-there-a-windows-equivalent-of-nanosleep

Sleeping for us seems tricky on win, how about just:

#ifndef _WIN64 } while (dt > 1e-4_f64); // until dt <= 100us #else } while (dt > 1e-2_f64); // until dt <= 10ms #endif

1ms is more accurate ( 1/60 = 16.6 ms , 1/120 = 8.3ms , 1/40 = 25 ms )

#else } while (dt > 1e-3_f64); // until dt <= 1ms #endif

JYLeeLYJ · 2020-07-30T08:19:40Z

taichi/system/timer.cpp

+    if (dt <= 0) {
+      return;
+    }
+    Time::sleep(dt * 1e-3);


We set the precision as 100us. But relatively , dt * 1e-3 is too small .
As a result , Sleep(0) is always called on windows , which will not give up the CPU time slice usually.
I think Time::sleep(dt) or Time::sleep(dt * 0.5) is enough.

Note that the unit of (t - Time::get_time()) is seconds, while the unit of Time::sleep is milliseconds.

Time::sleep should be seconds . See Time::usleep(s * 1e6_f64) .
Here are some actual value while running :
dt = 0.011... , dt = 0.008... and dt * 1e-3 is about 10 us

…ui-fps-limit

archibate · 2020-08-01T03:41:16Z

Hi, given that it's impossible to sleep for < 1ms on win, I simply abandoned reduce-idle-power-consumption there, WDYT about this change? Feel free to request change if you found a solution for this :)

JYLeeLYJ

dt * 0.4 may be an enough scale . If it's ok , here is no need to ban on Windows .
It's still possible to reduce CPU usage at milliseconds level .

while dt is at seconds or milliseconds level , Sleep is work .
while dt is under 1ms , using Sleep(0) is just like polling with for-loop.

In addition , for the frame rate accuracy , we just need to using that more accurate implementation win_sleep I suggested above (using WIN multimedia timer api and waitable event ), instead of Sleep which sometimes could lead to 1 ~ 10 ms error .
I can help u take an additional commit and test for this : )

taichi/system/timer.cpp

JYLeeLYJ · 2020-08-01T05:35:10Z

taichi/system/timer.cpp

+    if (dt <= 0) {
+      return;
+    }
+    Time::sleep(dt * (dt < 4e-2_f64 ? 0.02 : 0.4));


Is any difference here ( using 0.02 or 0.4 )?
Why not just use :

Suggested change

Time::sleep(dt * (dt < 4e-2_f64 ? 0.02 : 0.4));

Time::sleep(dt * 0.4);

This ensures that the dt of sleep is more accurate when small; without this, I found the FPS to be around 59; with this, I found the FPS to be accurately 60.00.

Co-authored-by: JYLeeLYJ <30959553+JYLeeLYJ@users.noreply.github.com>

archibate · 2020-08-03T04:40:25Z

In addition , for the frame rate accuracy , we just need to using that more accurate implementation win_sleep I suggested above (using WIN multimedia timer api and waitable event ), instead of Sleep which sometimes could lead to 1 ~ 10 ms error .
I can help u take an additional commit and test for this : )

That would be great! I invited you to archibate/taichi so that you could push to this branch, would you mind:

Implement a win_sleep of us precision in this PR?
In another PR and left #ifndef _WIN64 in this PR?

…Time::sleep

JYLeeLYJ · 2020-08-03T21:33:53Z

I have added win_usleep , win_msleep for different use cases on Windows .
None behavior changes on Linux. You can try to run on your machine to check if anything is different : )

archibate · 2020-08-04T15:28:00Z

taichi/system/timer.cpp

@@ -57,18 +57,82 @@ double Time::get_time() {
 }
 #endif

+#ifdef _WIN64
+#include <Windows.h>
+#pragma comment(lib, "Winmm.lib")


I have added win_usleep , win_msleep for different use cases on Windows .
None behavior changes on Linux. You can try to run on your machine to check if anything is different : )

Nice work! I can confirm that it's running happily on my machine!
One concern, what is Winmm.lib? Will it cause compat issue?
We'd better include it in CMakeList.txt instead of an inline #pragma comment, WDYT?
I'd like to provide more usage about linking libraries in CMake if you are not familiar to.

Winmm.lib is just a system multimedia API , which contains high resolution timer event functions .
Winmm.dll could be found in system path . And the minimum support client is winXP . This might not cause incompatibility problem.
See : MSDN

At the last commit I have moved #pragma commit away and used target_link_library instead .

cmake/TaichiCore.cmake

python/taichi/cc_compose.py

[GUI] Support gui.fps_limit and reduce idle power consumption

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archibate requested review from k-ye, yuanming-hu, JYLeeLYJ and taichi-gardener and removed request for k-ye and yuanming-hu July 30, 2020 01:31

taichi-gardener and others added 2 commits July 29, 2020 21:31

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archibate added 2 commits July 31, 2020 15:59

yste rge branch 'gui-fps-limit' of github.com:archibate/taichi into g…

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…ui-fps-limit

treat win to until dt <= 1ms

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archibate self-assigned this Jul 31, 2020

archibate added 2 commits July 31, 2020 22:50

[skip ci] apply concern and down CPU usage to 7%

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[skip ci] sadly we drop win due to lack of usleep

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archibate requested a review from JYLeeLYJ August 1, 2020 03:52

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[skip ci] Apply suggestions from code review

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Co-authored-by: JYLeeLYJ <30959553+JYLeeLYJ@users.noreply.github.com>

[skip ci] enforce code format

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archibate requested a review from JYLeeLYJ August 3, 2020 04:37

JYLeeLYJ and others added 4 commits August 4, 2020 03:41

Add Time::msleep and use win_msleep, win_usleep on Windows.

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[skip ci] enforce code format

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[skip ci]use Sleep(0) in win_usleep and reset to use Time::usleep in …

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…Time::sleep

[skip ci] enforce code format

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Merge branch 'master' into gui-fps-limit

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archibate requested a review from xumingkuan August 4, 2020 15:28

archibate and others added 2 commits August 5, 2020 00:05

embrace anony namespace

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[skip ci] move Winmm.lib link option into cmake file.

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JYLeeLYJ approved these changes Aug 4, 2020

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archibate added 3 commits August 5, 2020 13:14

trigger CI

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Merge branch 'master' into gui-fps-limit

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[skip ci] codecov please happy

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archibate merged commit 5f2f216 into taichi-dev:master Aug 6, 2020

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[release] v0.6.25 #1668

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[GUI] Support gui.fps_limit and reduce idle power consumption #1611

[GUI] Support gui.fps_limit and reduce idle power consumption #1611

archibate commented Jul 30, 2020

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		@@ -69,6 +69,24 @@ void Time::sleep(double s) {
		Time::usleep(s * 1e6_f64);
		}

	Time::sleep(dt * (dt < 4e-2_f64 ? 0.02 : 0.4));
	Time::sleep(dt * 0.4);

[GUI] Support gui.fps_limit and reduce idle power consumption #1611

[GUI] Support gui.fps_limit and reduce idle power consumption #1611

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