We could also disable for, e.g., developer debug builds, but keep enabled on bots (there's some precedent in V8 for "fast snapshots" for local dev builds).
On Tue, Jul 16, 2024 at 5:26 PM Scott Violet <[email protected]> wrote: > The v8 snapshots provide substantial performance gains. Leszek provided > the data to back that up. We shouldn't remove them. The v8 team is in the > best position to answer if there are other strategies that could give the > same performance wins without having the additional build time. > > While I believe we shouldn't remove the snapshots, I sympathize with the > desire for faster builds. Seems like the thing we care about is ensuring we > don't regress test coverage. So, if we were to disable the snapshots on > many bots, we need to ensure we have at least one bot (on the main > waterfall) that is building the snapshots. > > -Scott > > On Mon, Jul 15, 2024 at 5:43 PM Nico Weber <[email protected]> wrote: > >> If the code path behind use_v8_context_snapshot is subtle and hard to get >> right, it sounds like there's our second reason for not having it, right >> there :) >> >> How much performance does the blink snapshot buy us? Is it possible to >> get some of that with less expensive techniques? >> >> (+sky who I think looked at this at some point.) >> >> On Monday, July 15, 2024 at 2:54:35 PM UTC-4 Leszek Swirski wrote: >> >>> +Michael Lippautz <[email protected]> >>> >>> I'm not sure we should do this for build time reasons alone. >>> `use_v8_context_snapshot` is the default behaviour in shipping browsers, >>> and it makes the renderer take quite a different path during page load / >>> navigation. If we disable it in regular builds, then regular builds >>> (including all the dchecks!) won't be running and texting the same code >>> that we're shipping. >>> >>> The fact that tests are failing with this flag change should be a huge >>> flashing red light about this proposal - if we make the tests not test the >>> code we're shipping, then we risk it breaking without us noticing. Indeed, >>> I've been trying to turn this flag on for Android, and have been struggling >>> to do so. >>> >>> - Leszek >>> >>> >>> On Mon, 15 Jul 2024, 20:25 Dave Tapuska, <[email protected]> wrote: >>> >>>> Have you thought about setting gn config v8_use_external_startup_data >>>> on any bots? >>>> >>>> I don't know why they are failing. The window constructor one is weird >>>> as well because the prototype chain is different... >>>> >>>> dave. >>>> >>>> On Mon, Jul 15, 2024 at 2:13 PM Nico Weber <[email protected]> wrote: >>>> >>>>> Hello, >>>>> >>>>> use_v8_context_snapshot causes us to build lots of files (blink + >>>>> dependencies) twice on bots that cross-compiler (win/arm64, android, etc). >>>>> >>>>> We'd like to turn off use_v8_context_snapshot in regular release >>>>> builds by default, and only keep it enabled in is_official_build builds. >>>>> >>>>> However, a small number of tests, almost all of >>>>> them inspector-protocol tests, fail if I try this: >>>>> https://chromium-review.googlesource.com/c/chromium/src/+/5704136 >>>>> >>>>> That's surprising to me. I would've expected use_v8_context_snapshot >>>>> to not change behavior. >>>>> >>>>> Does anyone have an idea why this might happen? >>>>> >>>>> Thanks, >>>>> Nico >>>>> >>>>> -- >>>>> You received this message because you are subscribed to the Google >>>>> Groups "blink-dev" group. >>>>> To unsubscribe from this group and stop receiving emails from it, send >>>>> an email to [email protected]. >>>>> To view this discussion on the web visit >>>>> https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CADZ1XibPV%3Dd448fckQeYFaO617_9aahsxysAjMEdQ4sy%3DQw4kQ%40mail.gmail.com >>>>> <https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CADZ1XibPV%3Dd448fckQeYFaO617_9aahsxysAjMEdQ4sy%3DQw4kQ%40mail.gmail.com?utm_medium=email&utm_source=footer> >>>>> . >>>>> >>>> -- >>>> You received this message because you are subscribed to the Google >>>> Groups "blink-dev" group. >>>> To unsubscribe from this group and stop receiving emails from it, send >>>> an email to [email protected]. >>>> >>> To view this discussion on the web visit >>>> https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CAHgVhZU-er_dfh_esgBmfLQ%2BOVf24y2yN7K6W6yjGqNkH%3Df%3D6w%40mail.gmail.com >>>> <https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CAHgVhZU-er_dfh_esgBmfLQ%2BOVf24y2yN7K6W6yjGqNkH%3Df%3D6w%40mail.gmail.com?utm_medium=email&utm_source=footer> >>>> . >>>> >>> -- You received this message because you are subscribed to the Google Groups "blink-dev" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CAGRskv-Nso4p3X-%3DEBPpi08h246gbjTRP8v7rVx%2BS3dH925%3D6A%40mail.gmail.com.
