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    Subject[tip: sched/core] x86: Print ratio freq_max/freq_base used in frequency invariance calculations
    The following commit has been merged into the sched/core branch of tip:

    Commit-ID: 24f326686c925a848d603a2c22f1f6ed1b7786e2
    Gitweb: https://git.kernel.org/tip/24f326686c925a848d603a2c22f1f6ed1b7786e2
    Author: Giovanni Gherdovich <ggherdovich@suse.cz>
    AuthorDate: Thu, 12 Nov 2020 19:26:14 +01:00
    Committer: Peter Zijlstra <peterz@infradead.org>
    CommitterDate: Thu, 03 Dec 2020 10:00:35 +01:00

    x86: Print ratio freq_max/freq_base used in frequency invariance calculations

    The value freq_max/freq_base is a fundamental component of frequency
    invariance calculations. It may come from a variety of sources such as MSRs
    or ACPI data, tracking it down when troubleshooting a system could be
    non-trivial. It is worth saving it in the kernel logs.

    # dmesg | grep 'Estimated ratio of average max'
    [ 14.024036] smpboot: Estimated ratio of average max frequency by base frequency (times 1024): 1289

    Signed-off-by: Giovanni Gherdovich <ggherdovich@suse.cz>
    Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
    Link: https://lkml.kernel.org/r/20201112182614.10700-4-ggherdovich@suse.cz
    ---
    arch/x86/kernel/smpboot.c | 1 +
    1 file changed, 1 insertion(+)

    diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
    index c5dd5f6..3577bb7 100644
    --- a/arch/x86/kernel/smpboot.c
    +++ b/arch/x86/kernel/smpboot.c
    @@ -2110,6 +2110,7 @@ static void init_freq_invariance(bool secondary, bool cppc_ready)
    if (ret) {
    init_counter_refs();
    static_branch_enable(&arch_scale_freq_key);
    + pr_info("Estimated ratio of average max frequency by base frequency (times 1024): %llu\n", arch_max_freq_ratio);
    } else {
    pr_debug("Couldn't determine max cpu frequency, necessary for scale-invariant accounting.\n");
    }
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