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Improve performance of applyMaskImageData #14766

Merged
merged 1 commit into from
Apr 9, 2022
Merged

Improve performance of applyMaskImageData #14766

merged 1 commit into from
Apr 9, 2022

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calixteman
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  • write some uint32 instead of uint8 to avoid the check before clamping;
  • unroll the loop to write data in the buffer
  • but keep a loop for the last element of a line: it likely doesn't hurt that much since it's executed only for one time for each line;
  • I tested on a macbook with an Apple chip, and on Firefox nightly the new code is almost 3.5x faster than before (~1.8x with Chrome).

@calixteman
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I measured the performances improvement with the pdf in https://bugzilla.mozilla.org/show_bug.cgi?id=878397.
I just open the first page, run each functions 100 times and computed the average time.
I got the following results in Firefox nightly (macbook pro M1):

For 100 runs, old: 13.760410000000084ms, new: 3.9957212499999697ms => 3.44x faster. 
For 100 runs, old: 11.18828541666674ms, new: 3.2841725000000044ms => 3.41x faster. 
For 100 runs, old: 11.076615416666673ms, new: 3.210079583333181ms => 3.45x faster.
For 100 runs, old: 11.120658750000075ms, new: 3.244162500000166ms => 3.43x faster. 
For 100 runs, old: 11.040089583333465ms, new: 3.299125833333292ms => 3.35x faster. 
For 100 runs, old: 11.082967083333351ms, new: 3.2127058333334206ms => 3.45x faster. 
For 100 runs, old: 11.006012083333443ms, new: 3.182824166666851ms => 3.46x faster. 
For 100 runs, old: 11.142017916666319ms, new: 3.218462083333325ms => 3.46x faster. 
For 100 runs, old: 13.580457500000248ms, new: 3.903052916667075ms => 3.48x faster. 
For 100 runs, old: 13.65221250000006ms, new: 3.9218341666663763ms => 3.48x faster. 
For 100 runs, old: 13.57868208333326ms, new: 3.9597995833329334ms => 3.43x faster. 
For 100 runs, old: 19.828106666666898ms, new: 5.813075000000026ms => 3.41x faster. 
For 100 runs, old: 13.406442500000121ms, new: 3.8805799999998998ms => 3.45x faster. 
For 100 runs, old: 10.512800416666504ms, new: 3.088225416666719ms => 3.40x faster. 
For 100 runs, old: 10.579237499999982ms, new: 3.078336666667019ms => 3.44x faster. 
For 100 runs, old: 10.544124583333796ms, new: 3.0949412499999016ms => 3.41x faster. 
For 100 runs, old: 13.468600833333257ms, new: 3.8730854166666178ms => 3.48x faster. 
For 100 runs, old: 13.375664999999717ms, new: 3.8885295833331472ms => 3.44x faster. 
For 100 runs, old: 13.551173333333063ms, new: 3.8657320833329867ms => 3.51x faster. 
For 100 runs, old: 13.32980250000015ms, new: 3.867634999999791ms => 3.45x faster. 
For 100 runs, old: 13.403179166665941ms, new: 3.862169583332943ms => 3.47x faster. 
For 100 runs, old: 13.52051583333312ms, new: 3.8448604166670703ms => 3.52x faster. 
For 100 runs, old: 13.358693333333285ms, new: 3.8543900000001305ms => 3.47x faster.

Snuffleupagus
Snuffleupagus approved these changes Apr 9, 2022
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Looks good to me, thank you!

src/shared/image_utils.js Outdated
mask >>= 1;
for (let i = 0; i < height; i++) {
for (const max = srcPos + widthInSource; srcPos < max; srcPos++) {
const elem = srcPos < src.length ? src[srcPos] : 255;
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Previously we computed this once at the start of the function, which seems more efficient overall. Hence, please re-introduce the srcLength variable and use that here and below.

src/shared/image_utils.js Outdated
Comment on lines 36 to 44
dest[destPos] = elem & 0b10000000 ? oneMapping : zeroMapping;
dest[destPos + 1] = elem & 0b1000000 ? oneMapping : zeroMapping;
dest[destPos + 2] = elem & 0b100000 ? oneMapping : zeroMapping;
dest[destPos + 3] = elem & 0b10000 ? oneMapping : zeroMapping;
dest[destPos + 4] = elem & 0b1000 ? oneMapping : zeroMapping;
dest[destPos + 5] = elem & 0b100 ? oneMapping : zeroMapping;
dest[destPos + 6] = elem & 0b10 ? oneMapping : zeroMapping;
dest[destPos + 7] = elem & 0b1 ? oneMapping : zeroMapping;
destPos += 8;
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Nit: Similar to this code in canvas.js, can we use the dest[destPos++] = ... format here as well since that (visually) aligns the code a tiny bit nicer?

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My goal is mainly to have some good perfs: a dest++ induces that the new value is stored in dest which is useless.
With this code we've only one store.

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I just tried the dest++ and it doesn't make any significative difference, let's go for it.

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I guess the counter can probably live in a register while it's in the loop scope and then the new value is stored only at the end of the main loop.

@calixteman
Improve performance of applyMaskImageData
687c9a8 
- write some uint32 instead of uint8 to avoid the check before clamping;
- unroll the loop to write data in the buffer
- but keep a loop for the last element of a line: it likely doesn't hurt
  that much since it's executed only for one time for each line;
- I tested on a macbook with an Apple chip, and on Firefox nightly the new
  code is almost 3.5x faster than before (~1.8x with Chrome).
@calixteman
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/botio test

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pdfjsbot commented Apr 9, 2022

From: Bot.io (Linux m4)

Received

Command cmd_test from @calixteman received. Current queue size: 0

Live output at: http://54.241.84.105:8877/b60892538e2232d/output.txt

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pdfjsbot commented Apr 9, 2022

From: Bot.io (Windows)

Received

Command cmd_test from @calixteman received. Current queue size: 0

Live output at: http://54.193.163.58:8877/939e6a85ec26ae6/output.txt

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pdfjsbot commented Apr 9, 2022

From: Bot.io (Linux m4)

Failed

Full output at http://54.241.84.105:8877/b60892538e2232d/output.txt

Total script time: 24.78 mins

  • Font tests: Passed
  • Unit tests: Passed
  • Integration Tests: Passed
  • Regression tests: FAILED
  different ref/snapshot: 5

Image differences available at: http://54.241.84.105:8877/b60892538e2232d/reftest-analyzer.html#web=eq.log

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pdfjsbot commented Apr 9, 2022

From: Bot.io (Windows)

Failed

Full output at http://54.193.163.58:8877/939e6a85ec26ae6/output.txt

Total script time: 26.42 mins

  • Font tests: Passed
  • Unit tests: FAILED
  • Integration Tests: Passed
  • Regression tests: FAILED
  different ref/snapshot: 1

Image differences available at: http://54.193.163.58:8877/939e6a85ec26ae6/reftest-analyzer.html#web=eq.log

@calixteman calixteman merged commit 2c135b0 into mozilla:master Apr 9, 2022
@Snuffleupagus Snuffleupagus mentioned this pull request May 8, 2022
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