Date: Thu, 21 Feb 2013 13:04:39 -0500 From: Mark Saad <nonesuch@longcount.org> To: "freebsd-hackers@freebsd.org" <freebsd-hackers@freebsd.org> Subject: Question on timecounter hardware / What cpu flag is constant_tsc Message-ID: <CAMXt9NYa6HT_Ee5q5jHepBWd5R7NCJRUzbbHU%2Brj%2BxfDnqO2Sw@mail.gmail.com>
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All I am looking into an issue with timecounter hardware on a number of HP DL165 G7's They all run FreeBSD 9.1-RELEASE and all have the same CPU and firmware. However they report strange results when you probe kern.timecounter.choice and kern.timecounter.hardware Take this example ssh root@ssr4 "sysctl kern.timecounter.choice" kern.timecounter.choice: TSC-low(-100) ACPI-safe(850) HPET(950) i8254(0) dummy(-1000000) ssh root@ssr4 "sysctl kern.timecounter.hardware" kern.timecounter.hardware: HPET dmidecode -s processor-version AMD Opteron(TM) Processor 6212 dmidecode -s processor-frequency 2600 MHz Unknown from dmesg.boot CPU: AMD Opteron(TM) Processor 6212 (2600.06-MHz K8-class CPU) Origin = "AuthenticAMD" Id = 0x600f12 Family = 15 Model = 1 Stepping = 2 Features=0x178bfbff<FPU,VME,DE,PSE,TSC,MSR,PAE,MCE,CX8,APIC,SEP,MTRR,PGE,MCA,CMOV,PAT,PSE36,CLFLUSH,MMX,FXSR,SSE,SSE2,HTT> Features2=0x1e98220b<SSE3,PCLMULQDQ,MON,SSSE3,CX16,SSE4.1,SSE4.2,POPCNT,AESNI,XSAVE,OSXSAVE,AVX> AMD Features=0x2e500800<SYSCALL,NX,MMX+,FFXSR,Page1GB,RDTSCP,LM> AMD Features2=0x1c9bfff<LAHF,CMP,SVM,ExtAPIC,CR8,ABM,SSE4A,MAS,Prefetch,OSVW,IBS,XOP,SKINIT,WDT,LWP,FMA4,NodeId,Topology,<b23>,<b2 4>> vs ssh root@ssr3 "sysctl kern.timecounter.choice" kern.timecounter.choice: TSC-low(1000) ACPI-safe(850) HPET(950) i8254(0) dummy(-1000000) ssh root@ssr3 "sysctl kern.timecounter.hardware" kern.timecounter.hardware: TSC-low dmidecode -s processor-version AMD Opteron(TM) Processor 6212 dmidecode -s processor-frequency 2600 MHz Unknown from dmesg.boot CPU: AMD Opteron(TM) Processor 6212 (2600.06-MHz K8-class CPU) Origin = "AuthenticAMD" Id = 0x600f12 Family = 15 Model = 1 Stepping = 2 Features=0x178bfbff<FPU,VME,DE,PSE,TSC,MSR,PAE,MCE,CX8,APIC,SEP,MTRR,PGE,MCA,CMOV,PAT,PSE36,CLFLUSH,MMX,FXSR,SSE,SSE2,HTT> Features2=0x1e98220b<SSE3,PCLMULQDQ,MON,SSSE3,CX16,SSE4.1,SSE4.2,POPCNT,AESNI,XSAVE,OSXSAVE,AVX> AMD Features=0x2e500800<SYSCALL,NX,MMX+,FFXSR,Page1GB,RDTSCP,LM> AMD Features2=0x1c9bfff<LAHF,CMP,SVM,ExtAPIC,CR8,ABM,SSE4A,MAS,Prefetch,OSVW,IBS,XOP,SKINIT,WDT,LWP,FMA4,NodeId,Topology,<b23>,<b2 4>> So my questions, what is the preferred time counter here ? In linux using TSC is preferred over hpet and to tell if you have a trusted TSC your cpu needs to support feature constant_tsc . Does anyone know what cpu feature this is; is it listed in my a fore mentioned dmesg.boot feature lists ? TIA -- mark saad | nonesuch@longcount.org
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