postgres-github.git / summary / log / commit / refs

commit    7fc36c5db55016f7a1d89b5e2efd82fe6fd39632
Author:   Andres Freund <andres@anarazel.de>
Date:     Thu Apr 09 15:50:24 2026 +0000

    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 <lukas@fittl.com>
    Reviewed-by: Andres Freund <andres@anarazel.de>
    Discussion: https://postgr.es/m/jr4hk2sxhqcfpb67ftz5g4vw33nm67cgf7go3wwmqsafu5aclq%405m67ukuhyszz

[parent: 60165db6e1f2]