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    SubjectRe: nmi_watchdog=2 regression in 2.6.21
    Daniel,

    On Fri, Aug 31, 2007 at 07:43:20AM -0700, Daniel Walker wrote:
    > On Thu, 2007-08-30 at 14:05 -0700, Stephane Eranian wrote:
    > > Daniel,
    >
    > > Yes, I realized I missed a small detail in the switch statement.
    > > Could you try the new version?
    >
    > This patch still has the stuck NMI .. Essentially the same thing that
    > happened without the patch..
    >
    Ok, looks like deaulting to P6 does not quite work.

    Here is a new version. This time I used a different approach.
    I am must admit I am a bit puzzled by the duplication of information
    between the wd_ops and the nmi_watchdog_ctlblk structure. My understanding
    is that thelater is used as a cache for the info that needs to be per-cpu.

    The wd_ops provides the MSR to use for the counter, yet all the setup_*()
    routines hardcode the MSR. Not sure why?

    In this patch, the setup_*() routine now extract the MSR from the wd_ops
    to copy them into the nmi_watchdog_ctlblk. This is not done for P4 because
    of the special and ugly case of HT.

    With this approach, we can now create a custom wd_ops for CoreDuo that is
    a clone of the intel_arch_wd_ops, except for the MSR.

    Could you try this one instead?

    Thanks.

    --

    -Stephane
    diff --git a/arch/i386/kernel/cpu/perfctr-watchdog.c b/arch/i386/kernel/cpu/perfctr-watchdog.c
    index 9b5d6af..f9066e1 100644
    --- a/arch/i386/kernel/cpu/perfctr-watchdog.c
    +++ b/arch/i386/kernel/cpu/perfctr-watchdog.c
    @@ -271,8 +271,8 @@ static int setup_k7_watchdog(unsigned nmi_hz)
    unsigned int evntsel;
    struct nmi_watchdog_ctlblk *wd = &__get_cpu_var(nmi_watchdog_ctlblk);

    - perfctr_msr = MSR_K7_PERFCTR0;
    - evntsel_msr = MSR_K7_EVNTSEL0;
    + perfctr_msr = wd_ops->perfctr;
    + evntsel_msr = wd_ops->evntsel;

    wrmsrl(perfctr_msr, 0UL);

    @@ -351,8 +351,8 @@ static int setup_p6_watchdog(unsigned nmi_hz)
    unsigned int evntsel;
    struct nmi_watchdog_ctlblk *wd = &__get_cpu_var(nmi_watchdog_ctlblk);

    - perfctr_msr = MSR_P6_PERFCTR0;
    - evntsel_msr = MSR_P6_EVNTSEL0;
    + perfctr_msr = wd_ops->perfctr;
    + evntsel_msr = wd_ops->evntsel;

    /* KVM doesn't implement this MSR */
    if (wrmsr_safe(perfctr_msr, 0, 0) < 0)
    @@ -577,8 +577,8 @@ static int setup_intel_arch_watchdog(unsigned nmi_hz)
    (ebx & ARCH_PERFMON_UNHALTED_CORE_CYCLES_PRESENT))
    return 0;

    - perfctr_msr = MSR_ARCH_PERFMON_PERFCTR1;
    - evntsel_msr = MSR_ARCH_PERFMON_EVENTSEL1;
    + perfctr_msr = wd_ops->perfctr;
    + evntsel_msr = wd_ops->evntsel;

    wrmsrl(perfctr_msr, 0UL);

    @@ -613,6 +613,16 @@ static struct wd_ops intel_arch_wd_ops = {
    .evntsel = MSR_ARCH_PERFMON_EVENTSEL1,
    };

    +static struct wd_ops coreduo_wd_ops = {
    + .reserve = single_msr_reserve,
    + .unreserve = single_msr_unreserve,
    + .setup = setup_intel_arch_watchdog,
    + .rearm = p6_rearm,
    + .stop = single_msr_stop_watchdog,
    + .perfctr = MSR_ARCH_PERFMON_PERFCTR0,
    + .evntsel = MSR_ARCH_PERFMON_EVENTSEL0,
    +};
    +
    static void probe_nmi_watchdog(void)
    {
    switch (boot_cpu_data.x86_vendor) {
    @@ -623,6 +633,10 @@ static void probe_nmi_watchdog(void)
    wd_ops = &k7_wd_ops;
    break;
    case X86_VENDOR_INTEL:
    + if (boot_cpu_data.x86 == 6 && boot_cpu_data.x86_model == 14) {
    + wd_ops = &coreduo_wd_ops;
    + break;
    + }
    if (cpu_has(&boot_cpu_data, X86_FEATURE_ARCH_PERFMON)) {
    wd_ops = &intel_arch_wd_ops;
    break;
    \
     
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      Last update: 2007-08-31 18:25    [W:0.028 / U:61.076 seconds]
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