LGTM1 Thanks for working through this issue!!
On Wed, Nov 8, 2023 at 2:34 AM Domenic Denicola <[email protected]> wrote: > > > On Tue, Nov 7, 2023 at 5:42 PM François Beaufort <[email protected]> > wrote: > >> >> >> On Mon, Oct 30, 2023 at 7:39 PM Mike Taylor <[email protected]> >> wrote: >> >>> On 10/30/23 12:59 PM, Corentin Wallez wrote: >>> >>> On Fri, Oct 27, 2023 at 2:19 AM Domenic Denicola <[email protected]> >>> wrote: >>> >>>> >>>> >>>> On Thu, Oct 26, 2023 at 7:21 PM François Beaufort <[email protected]> >>>> wrote: >>>> >>>>> >>>>> >>>>> On Thu, Oct 26, 2023 at 11:05 AM Domenic Denicola < >>>>> [email protected]> wrote: >>>>> >>>>>> >>>>>> >>>>>> On Thu, Oct 26, 2023 at 5:21 PM 'François Beaufort' via blink-dev < >>>>>> [email protected]> wrote: >>>>>> >>>>>>> Contact emails >>>>>>> >>>>>>> [email protected], [email protected] >>>>>>> >>>>>>> Explainer >>>>>>> >>>>>>> https://github.com/gpuweb/gpuweb/issues/614 >>>>>>> >>>>>>> Specification >>>>>>> >>>>>>> https://gpuweb.github.io/gpuweb/#timestamp >>>>>>> >>>>>>> Summary >>>>>>> >>>>>>> WebGPU timestamp queries allow WebGPU applications to measure >>>>>>> precisely (down to the nanosecond) how much time their GPU commands >>>>>>> take to >>>>>>> execute, especially at the beginning and end of passes. Timestamp >>>>>>> queries >>>>>>> are heavily used to gain insights into the performance and behavior of >>>>>>> GPU >>>>>>> workloads. >>>>>>> >>>>>>> While the WebGPU specification makes timestamp queries an optional >>>>>>> feature due to timing attack concerns, we believe that timestamp queries >>>>>>> quantization provides a good middle ground by reducing the precision of >>>>>>> timers. To offer even more advanced protection against timing attacks >>>>>>> and >>>>>>> fingerprinting, timestamp queries are also coarsened based on site >>>>>>> isolation status: >>>>>>> >>>>>>> - Isolated contexts: timestamp queries are exposed with a resolution >>>>>>> of 100 microseconds. >>>>>>> >>>>>>> - Non-isolated contexts: timestamp queries are not exposed at all. >>>>>>> >>>>>> >>>>>> By "isolated" do you mean "has the cross-origin isolated capability >>>>>> <https://html.spec.whatwg.org/#concept-settings-object-cross-origin-isolated-capability> >>>>>> "? >>>>>> >>>>> >>>>> Yes. >>>>> >>>>> >>>>>> >>>>>> I wasn't able to find any spec or tests for this requirement, which >>>>>> seems like a potential interoperability issue. >>>>>> >>>>> >>>>> The WebGPU spec currently says: "The feature is optional, and a WebGPU >>>>> implementation may limit its exposure only to those scenarios that are >>>>> trusted." >>>>> See >>>>> https://gpuweb.github.io/gpuweb/#security-timing:~:text=The%20feature%20is%20optional%2C%20and%20a%20WebGPU%20implementation%20may%20limit%20its%20exposure%20only%20to%20those%20scenarios%20that%20are%20trusted >>>>> >>>> >>>> I realize that. I was suggesting that, for interoperability purposes, >>>> you should consider specifying the actual condition, instead of leaving it >>>> vague and optional. (E.g. at least in other standards bodies, we have >>>> guidance to avoid optional or implementation-defined features; instead, we >>>> try to work together with other browser engines to come to a common, >>>> interoperable implementation, backed by a test suite.) >>>> >>>> I hope the API Owners can consider this when deciding whether or not to >>>> approve, as I believe that letting these sorts of non-specified and >>>> non-tested features be shipped is harmful for the platform's health. >>>> >>>> >>> I'll add discussion of that to the agenda for this week's WebGPU >>> meeting: can we agree on the availability of timestamp queries (provided >>> there is hardware support) and the quantization depending on contexts. (but >>> to be perfectly honest I think we'll have pushback). Of course the WebGPU >>> standard body tries to avoid implementation-defined features, and instead >>> have deterministic and tested features, but timestamps is one of the ones >>> that might need to be an exception to it. Let's see what consensus the >>> group comes to! >>> >>> >>> Thank you - looking forward to the update. >>> >> >> Good news! The members of the GPU for the Web Community Group have accepted >> a proposal >> <https://github.com/gpuweb/gpuweb/issues/4175#issuecomment-1789865938> >> to allow timestamps regardless of site isolation, always with the >> non-isolated resolution from hr-time >> <https://w3c.github.io/hr-time/#dfn-coarsen-time> (100us). >> Check out the spec PR at https://github.com/gpuweb/gpuweb/pull/4359 and >> updated spec at https://gpuweb.github.io/gpuweb/#security-timing. This >> decision aims to address the interoperability concerns raised earlier. >> > > That's great! Using the same time resolution as the rest of the platform > makes sense, and this definitely addresses my interop concerns. Thanks to > you and the group for making this change! > > > -- > 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/CAM0wra_p2U%2BwqkMrhH12DgMzph_77Ps4xk0Bn_ZspD%2BWEYzuqA%40mail.gmail.com > <https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CAM0wra_p2U%2BwqkMrhH12DgMzph_77Ps4xk0Bn_ZspD%2BWEYzuqA%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]. 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