Messages in this thread | | | From | "Chen, Yu C" <> | Subject | RE: [PATCH][v5] x86, suspend: Save/restore extra MSR registers for suspend | Date | Mon, 16 Nov 2015 15:20:00 +0000 |
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Hi, Boris,
> -----Original Message----- > From: Borislav Petkov [mailto:bp@suse.de] > Sent: Tuesday, October 13, 2015 12:38 AM > To: Chen, Yu C > Cc: mingo@redhat.com; rjw@rjwysocki.net; pavel@ucw.cz; > tglx@linutronix.de; hpa@zytor.com; Zhang, Rui; luto@kernel.org; > linux@horizon.com; dsmythies@telus.net; linux-pm@vger.kernel.org; > x86@kernel.org; linux-kernel@vger.kernel.org; Kaszewski, Marcin > Subject: Re: [PATCH][v5] x86, suspend: Save/restore extra MSR registers for > suspend > > On Sun, Oct 11, 2015 at 11:20:01AM +0800, Chen Yu wrote: > > A bug is reported(https://bugzilla.redhat.com/show_bug.cgi?id=1227208) > > I get: > > "You are not authorized to access bug #1227208. > > Most likely the bug has been restricted for internal development processes > and we cannot grant access." > > > that, after resumed from S3, CPU is running at a low speed. > > After investigation, it is found that, BIOS has modified the value of > > THERM_CONTROL register during S3, and changes it from 0 to 0x10 (thus > > changes the clock modulation from reserved to enabled), since value of > > 0x10 means CPU can only get 25% of the Duty Cycle, this triggers the > > problem. > > Is this what the bug described above is? In any case, please remove the > private bugzilla link and describe the bug in text here. Yes, this bug is described in the changelog, I'll remove the link. > > Also, from reading the other thread about the v4 patch, it sounds like > intel_pstate can't handle the clock modulation properly, according to what > Doug says. As discussed with Doug in the v4 patch, the problem brought by clock modulation is because intel_pstate use a theoretical pstate to calculate the cpu busy ratio, and Doug has proposed a patch to use compensatory algorithm in intel_pstate, to predict the pstate based on actual cpu freq(take clock modulation into account), which can fix his problem now. So I'll resend a version 6 of current patch, because some server in production environment has suffered from this problem for some time.. thanks.
Best regards, Yu
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