On Thu, Dec 24, 2020 at 03:34:33PM +1100, Jonathan Gray wrote:
> On Thu, Dec 24, 2020 at 12:42:23AM +0000, James Cook wrote:
> > On Wed, Dec 23, 2020 at 08:43:10PM +0000, James Cook wrote:
> > > On Wed, Dec 23, 2020 at 11:47:05PM +1100, Jonathan Gray wrote:
> > > > On Wed, Dec 23, 2020 at 12:31:10PM +1100, Jonathan Gray wrote:
> > > > > On Tue, Dec 22, 2020 at 06:30:48PM +0000, James Cook wrote:
> > > > > > > + case 0xa6: /* Coffeelake mobile */
> > > > > >
> > > > > > The laptop's CPU is an i7-10710U, which I think is in the Comet Lake
> > > > > > series, not Coffee Lake.
> > > > >
> > > > > Yes 0xa6 is comet lake.
> > > > >
> > > > > But we should really do what FreeBSD and Linux do and fallback to
> > > > > cpuid 0x16 as Intel keeps creating new skylake variants.
> > > > >
> > > > > The frequency from cpuid 0x15 is Hz, from 0x16 it is MHz.
> > > > >
> > > > > Untested as I don't have any >= skylake machines.
> > > > > If you can add a printf to check the value is sane that would
> > > > > be helpful.
> > > >
> > > > As noticed by tb@ the last diff wasn't quite right:
> > > >
> > > > Index: sys/arch/amd64/amd64/tsc.c
> > > > ===================================================================
> > > > RCS file: /cvs/src/sys/arch/amd64/amd64/tsc.c,v
> > > > retrieving revision 1.21
> > > > diff -u -p -r1.21 tsc.c
> > > > --- sys/arch/amd64/amd64/tsc.c 6 Sep 2020 20:50:00 -0000 1.21
> > > > +++ sys/arch/amd64/amd64/tsc.c 23 Dec 2020 12:25:32 -0000
> > > > @@ -66,14 +66,16 @@ tsc_freq_cpuid(struct cpu_info *ci)
> > > > eax = ebx = khz = dummy = 0;
> > > > CPUID(0x15, eax, ebx, khz, dummy);
> > > > khz /= 1000;
> > > > - if (khz == 0) {
> > > > + /*
> > > > + * Fallback to 'Processor Base Frequency' from cpuid
> > > > 0x16 when
> > > > + * 'nominal frequency of the core crystal clock' from
> > > > cpuid 0x15
> > > > + * is 0 on >= Skylake
> > > > + */
> > > > + if (khz == 0 && cpuid_level >= 0x16) {
> > > > + CPUID(0x16, khz, dummy, dummy, dummy);
> > > > + khz = khz * 1000 * eax / ebx;
> > > > + } else if (khz == 0) {
> > > > switch (ci->ci_model) {
> > > > - case 0x4e: /* Skylake mobile */
> > > > - case 0x5e: /* Skylake desktop */
> > > > - case 0x8e: /* Kabylake mobile */
> > > > - case 0x9e: /* Kabylake desktop */
> > > > - khz = 24000; /* 24.0 MHz */
> > > > - break;
> > > > case 0x5f: /* Atom Denverton */
> > > > khz = 25000; /* 25.0 MHz */
> > > > break;
> > >
> > > The patch works (I tested bsd.rd; sleep and date both behave right).
> > >
> > > Based on added printfs, it ends up with a khz of 23880, computed as
> > > 1600 * 1000 * 2 / 134.
> >
> > I noticed something strange about the hw.setperf and hw.cpuspeed
> > sysctls. I don't know if they're related to the original bug or its
> > fix.
> >
> > My hw.cpuspeed sysctl starts out at 16264, which seems way too high.
> > This page
> >
> >
> > https://ark.intel.com/content/www/us/en/ark/products/196448/intel-core-i7-10710u-processor-12m-cache-up-to-4-70-ghz.html
> >
> > claims a "Max Turbo Frequency" of 4.70 GHz.
> >
> > hw.setperf seems to start out at 1320, as indicated by sysctl output
> > when I change it. Of course, if I lower it, I can't bring it back to
> > 1320. If I set it to 100, hw.cpuspeed is a more plausible 1601.
>
> The max + 1 state is the turbo state.
>
> As for why cpuspeed is so high, have a look at
> sys/arch/amd64/amd64/identcpu.c cpu_freq() can you confirm if
> cpu_freq_ctr() returns a non zero value? If so there is something wrong
> with the performance counter method of getting cpuspeed.
I added a printf (below) in cpu_freq; cpu_freq_ctr is indeed returning
non-zero (so my second printf is not reached). It gets called a few
times; the first time it's 16263595810 and the other times it's
approximately 3890938820 (it varies a bit).
I didn't understand your comment about the turbo state and max+1... I'm
seeing an initial value of 1320 for hw.setperf and I thought max for it
is 100.
On the bright side, install68.img from the latest snapshot just installed
OpenBSD on this laptop without trouble; thanks for getting that checked in!
diff --git a/sys/arch/amd64/amd64/identcpu.c b/sys/arch/amd64/amd64/identcpu.c
index 0a3d7dfea06..ad07a120671 100644
--- a/sys/arch/amd64/amd64/identcpu.c
+++ b/sys/arch/amd64/amd64/identcpu.c
@@ -454,6 +454,7 @@ cpu_freq(struct cpu_info *ci)
uint64_t last_count, count;
count = cpu_freq_ctr(ci);
+ printf("YYY count is %llu\n", count);
if (count != 0)
return (count);
@@ -461,6 +462,7 @@ cpu_freq(struct cpu_info *ci)
delay(100000);
count = rdtsc();
+ printf("YYY count is %llu; last_count is %llu\n", count, last_count);
return ((count - last_count) * 10);
}
--
James
