On Fri 2017-02-17 16:27:30, Chen Yu wrote: > Previously a bug was reported that on certain Broadwell > platform, after resumed from S3, the CPU is running at > an anomalously low speed, due to the BIOS has enabled the > MSR throttling across S3. The solution to this was to introduce > a quirk framework to save/restore tstate MSR register around > suspend/resume, in Commit 7a9c2dd08ead ("x86/pm: > Introduce quirk framework to save/restore extra MSR > registers around suspend/resume"). > > However there are still three problems left: > 1. More and more reports show that other platforms also > encountered the same issue, so the quirk list might > be endless. > 2. Each CPUs should take the save/restore operation into > consideration, rather than the boot CPU alone. > 3. Normally ACPI T-state re-evaluation is done on resume, > however there is no _TSS on the bogus platform, thus > above re-evaluation code does not run on that machine. > > Solution: > This patch is based on the fact that, we generally should not > expect the system to come back from resume with throttling > enabled, but leverage the OS components to deal with it, > such as thermal event. So we simply clear the MSR T-state > and print the warning if it is found to be enabled after > resumed back. Besides, we can remove the quirk in previous patch > later.
What if the machine _is_ hot? > +static int acpi_throttling_init_ops(void) > +{ > + /* > + * Reevaluate on boot CPU. Since it is not always CPU0, > + * we can not invoke throttling_msr_reevaluate(0) directly. > + */ Boot cpu is not cpu#0? How can that be? Should we introduce generic framework to "fix" all the cpus? Actually, should this be done right on cpu hotplug? Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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