Thank you Sangwhan, this makes sense. I added this github issue: https://github.com/WICG/cpu-performance/issues/18
On Tuesday, July 21, 2026 at 9:53:49 PM UTC+2 Sangwhan Moon wrote: > Specifically, on ChromeOS if you are in power saving mode cores are pulled > offline or downclocked. > > So without an observer mechanism - if you load a an app while battery > saver is active you'll be stuck in degraded mode until you reload. The only > workaround would be for the app to poll and see if the core config changed, > but this would be an antipattern (there is no "battery saver event" exposed > to the web, as it allows for correlating users. > > That thread can be pulled from here: > https://source.chromium.org/search?q=HotplugCpuAction&sq=&ss=chromiumos%2Fchromiumos%2Fcodesearch:src%2Fplatform2%2Fresourced%2Fsrc%2F > > One other minor bit that comes to mind is how this would work with DVFS > <https://developer.arm.com/documentation/100960/0100/Dynamic-Voltage-and-Frequency-Scaling>, > > if frequency is used for bucketing and the read time is pre-ramp. > > On Tue, Jul 21, 2026 at 11:35 AM Nikolaos Papaspyrou < > [email protected]> wrote: > >> Further to Rick's answer to Alex, let me address the remaining questions >> and comments. >> >> The statements of support from Adobe and Figma came before the OT (and >> before the API was even implemented). The statement from Zoom came during >> the OT. I think it shows that Zoom would benefit both from static and from >> dynamic information. It is not clear to me whether they are aware of the >> Compute Pressure API or if, for some reason, it does not meet their needs. >> As I understand it, the last example that I included shows the intended use >> case for both , and that’s my interpretation of how Zoom intends to use it. >> I am not aware of code using this API that is publicly available at the >> moment. >> >> As I have already mentioned, we have not received any substantial, >> actionable or negative feedback from partners that participate in the OT. >> As a result, we have not changed anything in the API itself. Since the >> first implementation, however, we have introduced all appropriate overrides >> in Chrome for the value returned by `navigator.cpuPerformance`: a user >> setting, an enterprise policy, and a DevTools override for simulation and >> CPU throttling (work in progress). >> >> Regarding Sangwhan’s questions about CPU hot plugging, the spec of this >> API makes it clear that the value returned by `navigator.cpuPerformance` >> depends on the CPU model and number of cores. If any of these change, e.g., >> because of hot plugging, it is reasonable to expect that the reported value >> may change. In fact, the current implementation in Chrome will update the >> value in new renderers (but it will not change the value in existing ones). >> >> If hot plugging represents a significant use case, it may be reasonable >> to add some sort of observer to the spec, similarly to what the Compute >> Pressure API does. I will open an github issue to discuss this on the spec. >> >> Regarding Sangwhan’s comment about a “web app loaded in power saving >> mode, followed by the user plugging in a charger”, as we have explained, >> the API reports static information and should normally have nothing to do >> with power saving or plugging in the charger — *unless* of course these >> actions affect the CPU model and/or the number of cores reported by the OS, >> in which case they will be treated similarly to how hot plugging will be >> treated. >> >> Best regards, >> Nikos. >> >> On Tuesday, July 21, 2026 at 8:24:22 PM UTC+2 Rick Byers wrote: >> >>> Hey Alex, >>> Google Meet has long relied on an extension to get this data, and now, >>> after extensive testing in the OT, plans to switch to this API to >>> preserve their existing use cases. Personally I think that, along with >>> the statements of support from Zoom and others, is sufficient to easily >>> clear our I2S bar. WDYT? >>> >>> Rick >>> >>> On Mon, Jul 20, 2026 at 2:57 PM Alex Russell <[email protected]> >>> wrote: >>> >>>> I appreciate the updates, Nikolaos. Thanks, in particular, for updating >>>> the examples. >>>> >>>> I'm concerned that none of the statements of interest linked above >>>> (which I had missed; appreciate the pointers) actually discuss using the >>>> API in any way, and Zoom's reply seems to suggest that they either are not >>>> aware of compute pressure, or need changes in order to provide UI for >>>> their >>>> users. >>>> >>>> Do you have substantive feedback from the Origin Trials from users that >>>> benefited? Did they suggest any API or behaviour changes? Did you make >>>> changes as a result? And do you have any view to the hotplug question >>>> Sangwhan asked? Are you looking to add events to describe changes in a >>>> future update to the API? >>>> >>>> Best, >>>> >>>> Alex >>>> >>>> On Thursday, July 16, 2026 at 12:58:37 PM UTC-7 Vladimir Levin wrote: >>>> >>>>> LGTM3 >>>>> >>>>> On Thu, Jul 16, 2026 at 3:38 PM Mike Taylor <[email protected]> >>>>> wrote: >>>>> >>>>>> LGTM2 >>>>>> On 7/16/26 1:03 p.m., Chris Harrelson wrote: >>>>>> >>>>>> Thanks! >>>>>> >>>>>> LGTM1 >>>>>> >>>>>> On Thu, Jul 16, 2026 at 10:56 AM Nikolaos Papaspyrou < >>>>>> [email protected]> wrote: >>>>>> >>>>>>> My apologies for misspelling the name above. :-( -- >>>>>>> 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 visit >>>>>>> https://groups.google.com/a/chromium.org/d/msgid/blink-dev/b9cd6dbc-ab5b-4335-b9fb-f92e7b377d5dn%40chromium.org >>>>>>> >>>>>>> <https://groups.google.com/a/chromium.org/d/msgid/blink-dev/b9cd6dbc-ab5b-4335-b9fb-f92e7b377d5dn%40chromium.org?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 visit >>>>>> https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CAOMQ%2Bw93hvYAtxM2Do3pZndYuqpjSd%2BYCuFBeAtjFeFXDb1Krg%40mail.gmail.com >>>>>> >>>>>> <https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CAOMQ%2Bw93hvYAtxM2Do3pZndYuqpjSd%2BYCuFBeAtjFeFXDb1Krg%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 visit >>>>>> https://groups.google.com/a/chromium.org/d/msgid/blink-dev/563f5831-8546-4a90-9d05-f294cd8d5caf%40chromium.org >>>>>> >>>>>> <https://groups.google.com/a/chromium.org/d/msgid/blink-dev/563f5831-8546-4a90-9d05-f294cd8d5caf%40chromium.org?utm_medium=email&utm_source=footer> >>>>>> . >>>>>> >>>>> -- You received this message because you are subscribed to the Google Groups "blink-dev" group. 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