1524299 - Don't detect Intel M processors with varying clock speeds as low-end

Status: RESOLVED WONTFIX

(Firefox :: General, enhancement, P3)

Description

[:Gijs (out for now; he/him)]

Intel M processors can have a base clock speed of e.g. 1.2Ghz, and then a "turbo mode" of e.g. 2.9Ghz. It seems these get registered as "just" 1.2Ghz and it throws off our detection.

:chutten, do you know if we have the top speed information anywhere else (please forward as appropriate!)? I guess we have processor info somewhere else if all else fails, but I'd prefer not to rely on that...

Comment 1

[Chris H-C :chutten]

As far as I know we don't have anything more than we're currently reporting via sysinfo. The Telemetry Environment only has access to a single MHz. The mechanism we get this from is getSysInfoProperty("cpuspeed", ...), which gets this (on Windows) from the registry thusly.

Looks like we use WMI Classes in nsAppRunner to query a few things. Maybe we can get it to look up a Win32_Processor array for us and make MaxClockSpeed available on sysinfo?

Since I'm not the person to ask, the person I'd ask about these things is :aklotz.

Comment 2

[(No longer employed by Mozilla) Aaron Klotz]

Looks to me like issuing the CPUID instruction would do the trick: its output contains flags indicating whether turbo boost is present, and also provides baseline and maximum clock speeds. Of course, the CPUID output format differs between Intel and AMD chips, so be careful. Note that there is a compiler intrinsic for CPUID.

Though I suppose WMI would probably abstract the processor differences away, but WMI is not exactly a lightweight API either ;-)

Comment 3

[:Gijs (out for now; he/him)]

Wontfixing this as we'll be removing this code.