Messages in this thread |  | | Subject | Re: Error in x86 CPU capabilities starting with test5/6 | Date | Fri, 17 Nov 2000 12:10:07 +0000 (GMT) | From | Alan Cox <> |
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> > You have a user-space program which parses /proc/cpuinfo instead of > > executing CPUID itself, so it breaks. > > Arguably, it is always better to parse /proc/cpuinfo instead of executing
Actually this is definitively the case.
It is not safe to use cpuid to check the availability of RDTSC in Linux because the CPU itself does not know if the TSC is buggy (Some MediaGX, some WinChip,..) or if the TSC on an SMP box is constant across all processors.
Even checking the cpuinfo for the TSC should be done with care, and its far far better to use gettimeofday unless doing very tiny timings (eg for optimising code paths)
Alan
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