instrumentation: Avoid CPUID 0x15/0x16 for Hypervisor TSC frequency This restricts the retrieval of the TSC frequency whilst under a Hypervisor to either Hypervisor-specific CPUID registers (0x40000010), or TSC calibration. We previously allowed retrieving from the traditional CPUID registers for TSC frequency (0x15/0x16) like on bare metal, but it turns out that they are not trustworthy when virtualized and can report wildly incorrect frequencies, like 7 kHz when the actual calibrated frequencty is 2.5 GHz.
Per report from buildfarm member drongo. Author: Lukas Fittl <[email protected]> Reviewed-by: Andres Freund <[email protected]> Discussion: https://postgr.es/m/jr4hk2sxhqcfpb67ftz5g4vw33nm67cgf7go3wwmqsafu5aclq%405m67ukuhyszz Branch ------ master Details ------- https://git.postgresql.org/pg/commitdiff/7fc36c5db55016f7a1d89b5e2efd82fe6fd39632 Modified Files -------------- src/port/pg_cpu_x86.c | 21 +++++++++------------ 1 file changed, 9 insertions(+), 12 deletions(-)
