Date: Wed, 22 Oct 2008 12:02:40 -0400 From: John Baldwin <jhb@freebsd.org> To: Jung-uk Kim <jkim@freebsd.org> Cc: svn-src-head@freebsd.org, svn-src-all@freebsd.org, src-committers@freebsd.org Subject: Re: svn commit: r184146 - in head/sys: amd64/amd64 amd64/include i386/i386 i386/include Message-ID: <200810221202.40803.jhb@freebsd.org> In-Reply-To: <200810221141.52036.jkim@FreeBSD.org> References: <200810220001.m9M01rLq011948@svn.freebsd.org> <200810221101.37788.jhb@freebsd.org> <200810221141.52036.jkim@FreeBSD.org>
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On Wednesday 22 October 2008 11:41:36 am Jung-uk Kim wrote: > On Wednesday 22 October 2008 11:01 am, John Baldwin wrote: > > On Tuesday 21 October 2008 08:01:53 pm Jung-uk Kim wrote: > > > Author: jkim > > > Date: Wed Oct 22 00:01:53 2008 > > > New Revision: 184146 > > > URL: http://svn.freebsd.org/changeset/base/184146 > > > > > > Log: > > > Set kern.timecounter.invariant_tsc to 1 for AMD CPU family 10h > > > and higher even if BIOS does not advertise it. > > > > > > Modified: > > > head/sys/amd64/amd64/identcpu.c > > > head/sys/amd64/include/specialreg.h > > > head/sys/i386/i386/identcpu.c > > > head/sys/i386/include/specialreg.h > > > > > > Modified: head/sys/amd64/amd64/identcpu.c > > > > =================================================================== > >=========== > > > > > --- head/sys/amd64/amd64/identcpu.c Tue Oct 21 23:36:28 > > > 2008 (r184145) +++ head/sys/amd64/amd64/identcpu.c Wed Oct 22 > > > 00:01:53 2008 (r184146) @@ -348,7 +348,9 @@ printcpuinfo(void) > > > cpu_feature &= ~CPUID_HTT; > > > > > > if (!tsc_is_invariant && > > > - (amd_pminfo & AMDPM_TSC_INVARIANT)) { > > > + (strcmp(cpu_vendor, "AuthenticAMD") == 0 && > > > + ((amd_pminfo & AMDPM_TSC_INVARIANT) != 0 || > > > + AMD64_CPU_FAMILY(cpu_id) >= 0x10))) { > > > tsc_is_invariant = 1; > > > printf("\n P-state invariant TSC"); > > > } > > > > Perhaps a simpler approach might be to just set AMDPM_TSC_INVARIANT > > for AMD64_CPU_FAMILY(cpu_id) >= 0x10? > > It seems Athlon X2 (Family 0Fh, Model 6Bh, Stepping G2) that I bought > also has invariant TSC although it is not advertised by CPUID. If > BIOS manufacturer decide to set the bit later, it should be honored > IMO. Err, yeah, my suggestion is something like this: /* * These CPUs have an invariant TSC even though they don't * always advertise it. */ if (strcmp(cpu_vendor, "AuthenticAMD") == 0 && AMD64_CPU_FAMILY(cpu_id) >= 0x10) amd_pminfo |= AMDPM_TSC_INVARIANT; if (!tsc_is_invariant && (amd_pminfo & AMDPM_TSC_INVARIANT)) { tsc_is_invariant; printf(...); } That will still support any other CPUs that grow the CPUID flag at some point, it just fakes the CPUID flag for CPUs that we know have it but just aren't advertising it. -- John Baldwin
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