1391602 - Budget throttling needs a notion of minimum budget amount

Status: RESOLVED FIXED

(Core :: DOM: Core & HTML, enhancement)

Description

[Andreas Farre [:farre]]

It's not enough to limit the lowest amount that we can schedule the timeout executor, since if we re-schedule we'll never decrease from that clamp (not until the budget has regenerated at least, which isn't what we want)

Comment 1

[Andreas Farre [:farre]]

Attachment: 0001-Bug-1391602-Clamp-execution-budget-to-a-minimum-valu.patch

Comment 2

[Ben Kelly [:bkelly, not reviewing]]

Comment on attachment 8898753 [details] [diff] [review]
0001-Bug-1391602-Clamp-execution-budget-to-a-minimum-valu.patch

Review of attachment 8898753 [details] [diff] [review]:
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So to make sure I understand...  The problem we had before this patch is we would limit the amount of delay, but the budget could end getting further and further behind.  Even if the page paused for a while it would have a very hard time getting out of the built-up negative budget deficit.

With this patch we avoid that by limiting how negative the budget can go.  This imposes the max delay like we used to have, but prevents the site from getting into a hole it can never recover from.

Is that accurate?

::: dom/base/TimeoutManager.cpp
@@ +97,5 @@
> +TimeDuration
> +GetMinBudget(bool aIsBackground)
> +{
> +  // The minimum budget is computed by looking up the maximum allowed
> +  // delay and computing how long time it would take to regenerate

nit: s/how long time it/how long it/

Comment 3

[Andreas Farre [:farre]]

Yes, but worse. If the executor got rescheduled it would be rescheduled to the same max value of the execution budget demanded a delay larger than that max value.

Comment 4

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/mozilla-inbound/rev/82c496b0a128
Clamp execution budget to a minimum value. r=bkelly

Comment 5

[Sebastian Hengst [:aryx] (needinfo me if it's about an intermittent or backout)]

https://hg.mozilla.org/mozilla-central/rev/82c496b0a128