+1 to double checking the benchmark
Most likely we're good as we should have at most a single idle rAF.
On Fri, 7 Feb 2025 at 20:13, Johnny Stenback <jstenb...@chromium.org> wrote:
> Hey Francois,
>
> This sounds promising. My one concern is what effect(s) this might have on
> our performance benchmarking work. +Camillo Bruni <cbr...@google.com> for
> his thoughts. We should at the very least make sure
> speedometer/motionmark/etc numbers are not negatively impacted by this
> change.
>
> Cheers,
> Johnny
>
> On Fri, Feb 7, 2025 at 10:03 AM Francois Pierre Doray <fdo...@chromium.org>
> wrote:
>
>> Hi,
>>
>> We tested an intervention on Canary/Dev/Beta that reduces the frame rate
>> by half (e.g., from 60fps to 30fps) after 4 consecutive frames without
>> pixel changes. The frame rate returns to normal immediately upon pixel
>> changes or input events. For example:
>>
>> let last = performance.now();
>> let c = () => {
>> window.requestAnimationFrame(c);
>> let now = performance.now();
>> console.log(now - last);
>> last = now;
>> }
>> c();
>>
>> The c() function's invocation frequency halves after 4 calls due to the
>> lack of pixel updates. Note: As a result, a subsequent frame with pixel
>> updates may be delayed by up to 1 frame (but frame rate returns to normal
>> immediately after a frame with pixel updates).
>>
>> This intervention significantly improves LCP, INP and CPU usage on Beta,
>> confirming our prior observation that no-op frames often occupy the main
>> thread during page load or input handling. To validate these results, we
>> need a 1% stable experiment (user behavior differs between pre-stable and
>> stable channels). Before proceeding, we'd appreciate feedback on potential
>> issues this experiment might cause. We will determine our next steps based
>> on input from this discussion.
>>
>> Thanks,
>>
>> François
>>
>> [cc: Chen, Li and Zheng, Hong from Intel who proposed and implemented
>> this intervention]
>>
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> Camillo Bruni | Software Engineer, V8 | Google Germany GmbH | Erika-Mann
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