Messages in this thread Patch in this message | | | From | Alexander Shishkin <> | Subject | Re: [PATCH v0 2/3] perf/x86/intel/pt: Export cpu frequency ratios needed by PT decoders | Date | Thu, 28 Apr 2016 18:55:49 +0300 |
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Alexander Shishkin <alexander.shishkin@linux.intel.com> writes:
> In order for Intel PT decoders to infer correct crystal clock and bus > frequencies that are required to correctly decode timing information > from a PT stream (MTC and CBR packets), export them as sysfs attributes: > > * max_nonturbo_ratio: ratio between the invariant TSC and base clock; > * tsc_art_ratio: TSC to core crystal clock ratio. > > Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
With a slightly better changelog:
From d0fbc4e45fb633e464cbbd61d6aacd5a476fd50d Mon Sep 17 00:00:00 2001 From: Alexander Shishkin <alexander.shishkin@linux.intel.com> Date: Wed, 19 Aug 2015 17:02:10 +0300 Subject: [PATCH] perf/x86/intel/pt: Export cpu frequency ratios needed by PT decoders
Intel PT decoders need access to various bits of timing related information to be able to correctly decode timing packets from a PT stream (MTC and CBR packets). This patch exports all the necessary bits as sysfs attributes for the sake of consistency:
* max_nonturbo_ratio: ratio between the invariant TSC and base clock; * tsc_art_ratio: TSC to core crystal clock ratio (also available as CPUID.15H).
Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com> --- arch/x86/events/intel/pt.c | 54 ++++++++++++++++++++++++++++++++++++++++++++++ arch/x86/events/intel/pt.h | 6 ++++++ 2 files changed, 60 insertions(+)
diff --git a/arch/x86/events/intel/pt.c b/arch/x86/events/intel/pt.c index e88915ff98..bf0b0fe33d 100644 --- a/arch/x86/events/intel/pt.c +++ b/arch/x86/events/intel/pt.c @@ -125,9 +125,46 @@ static struct attribute_group pt_format_group = { .attrs = pt_formats_attr, }; +static ssize_t +pt_timing_attr_show(struct device *dev, struct device_attribute *attr, + char *page) +{ + struct perf_pmu_events_attr *pmu_attr = + container_of(attr, struct perf_pmu_events_attr, attr); + + switch (pmu_attr->id) { + case 0: + return sprintf(page, "%lu\n", pt_pmu.max_nonturbo_ratio); + case 1: + return sprintf(page, "%u:%u\n", + pt_pmu.tsc_art_num, + pt_pmu.tsc_art_den); + default: + break; + } + + return -EINVAL; +} + +PMU_EVENT_ATTR(max_nonturbo_ratio, timing_attr_max_nonturbo_ratio, 0, + pt_timing_attr_show); +PMU_EVENT_ATTR(tsc_art_ratio, timing_attr_tsc_art_ratio, 1, + pt_timing_attr_show); + +static struct attribute *pt_timing_attr[] = { + &timing_attr_max_nonturbo_ratio.attr.attr, + &timing_attr_tsc_art_ratio.attr.attr, + NULL, +}; + +static struct attribute_group pt_timing_group = { + .attrs = pt_timing_attr, +}; + static const struct attribute_group *pt_attr_groups[] = { &pt_cap_group, &pt_format_group, + &pt_timing_group, NULL, }; @@ -140,6 +177,23 @@ static int __init pt_pmu_hw_init(void) int ret; long i; + rdmsrl(MSR_PLATFORM_INFO, reg); + pt_pmu.max_nonturbo_ratio = (reg & 0xff00) >> 8; + + /* + * if available, read in TSC to core crystal clock ratio, + * otherwise, zero for numerator stands for "not enumerated" + * as per SDM + */ + if (boot_cpu_data.cpuid_level >= CPUID_TSC_LEAF) { + u32 eax, ebx, ecx, edx; + + cpuid(CPUID_TSC_LEAF, &eax, &ebx, &ecx, &edx); + + pt_pmu.tsc_art_num = ebx; + pt_pmu.tsc_art_den = eax; + } + if (boot_cpu_has(X86_FEATURE_VMX)) { /* * Intel SDM, 36.5 "Tracing post-VMXON" says that diff --git a/arch/x86/events/intel/pt.h b/arch/x86/events/intel/pt.h index 3abb5f5ccc..e5385b1fa0 100644 --- a/arch/x86/events/intel/pt.h +++ b/arch/x86/events/intel/pt.h @@ -48,6 +48,9 @@ struct topa_entry { #define PT_CPUID_LEAVES 2 #define PT_CPUID_REGS_NUM 4 /* number of regsters (eax, ebx, ecx, edx) */ +/* TSC to Core Crystal Clock Ratio */ +#define CPUID_TSC_LEAF 0x15 + enum pt_capabilities { PT_CAP_max_subleaf = 0, PT_CAP_cr3_filtering, @@ -66,6 +69,9 @@ struct pt_pmu { struct pmu pmu; u32 caps[PT_CPUID_REGS_NUM * PT_CPUID_LEAVES]; bool vmx; + unsigned long max_nonturbo_ratio; + unsigned int tsc_art_num; + unsigned int tsc_art_den; }; /** -- 2.8.0.rc3
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