"Total frames" and "Janky frames" in dumpsys gfxinfo report

Question

I am calculating my Application performance using dumpsys gfxinfo command. After making performance improvement changes in my App code, I observed that Total number of frames and Janky frames count got drastically reduced.

What does decrease in "Total frames" count and "Janky Frames" count signify ? Is it good indicator of performance ?

Attached Performance reports.

After Performance improvements

################################
Total frames rendered: 1542

Janky frames: 584 (37.87%)

90th percentile: 81ms

95th percentile: 93ms

99th percentile: 129ms

Number Missed Vsync: 268

Number High input latency: 61

Number Slow UI thread: 471

Number Slow bitmap uploads: 15

Number Slow issue draw commands: 511

Total ViewRootImpl: 1

Total Views:        434

Total DisplayList:  505.57 kB
####################################

Before Performance improvements

###############################
Total frames rendered: 5185

Janky frames: 3229 (62.28%)

90th percentile: 101ms

95th percentile: 109ms

99th percentile: 121ms

Number Missed Vsync: 2487

Number High input latency: 65

Number Slow UI thread: 2088

Number Slow bitmap uploads: 75

Number Slow issue draw commands: 2967

Total ViewRootImpl: 1

Total Views:        435

Total DisplayList:  506.74 kB
######################################

Lautrec

Answer 1

"Total Frames" : Number of frames created to render . "Janky Frames" : Number of dropped frames. "Actual Frames rendered" : Total Frames - Janky Frames.

Even though increase in total Frames and decrease in Janky
Frames is good indicator of performance, thats not enough. Actual Number of frames rendered on screen in one second is the calculation which decides Performance health. More the number of frames rendered in one second means good performance.

Lautrec

Answer 2

Before use "dumpsys gfxinfo", you would use "adb shell dumpsys gfxinfo reset" to reset the framemetrics data in the system. Then do some operation on the screens you improved. Then use "dumpsys gfxinfo" .

Total frames rendered: The number of frame rendered from "reset" to "dumpsys gfxinfo". Janky frames: is the number of the frames that takes long than 16 ms, not the number of dropped frames.

The Janky Frame Rate is a very good data you can compare when improving the performance. In your case, you reduced the janky frame rate, 62.28% to 37.87%, which is very good.

Kansu

Isn't the frame which takes more than 16ms is dropped ??? then what is the difference between janky frames and dropped frames ? – Lautrec

Say a frame takes 64ms to render, that means 4 frames are dropped. – Kansu

for reset use: adb shell dumpsys gfxinfo <PACKAGE_NAME> reset – Economist

@hotpro, if a frame takes 64ms to render. Doesn`t that suppose to mean we have 1 janky frame and 3 dropped? Not all 4 dropped as you noted. – Fiction

Answer 3

The adb shell dumpsys gfxinfo <PACKAGE_NAME> command gives aggregated statistics about frame rendering across the entire lifetime of the process.

There are two things which should be keept in mind when interpreting the output:

• In the example you provided it is not clear for how long the two tests were executed, so it is useless for any interpretation. The gfxinfo output also provides time information uptime, realtime and stats since. To calculate the total time recored stats since - realtime or stats since - uptime needs to be calculated. realtime and uptime are most likely the same value (the difference bewteen the two is another topic)
• The total frames rendered increases only if there is anything to render. If gfxinfo is queried for a static user interface and no interactions or animations frames rendered is very very low. So the two outputs are only comparable if the same test was executed (exactly same ui interactions or animations).

To answer your questions:

What does decrease in "Total frames" count and "Janky Frames" count signify?

Decrease in Total frames could be less interactions or less time of gfxinfo recording. Decrease of Janky frames is basically the same and also more frames could be rendered and not have been dropped. This interpretation makes only sense if the same tests were applied in the two examples.

Is it good indicator of performance?

A decrease in janky frames is a good indicator of performance if (and only if) the same test for comparing two different implementations (e.g. of an animation) leads to the decrease in the optimized version of the two implementations.

Llovera