+++ /dev/null
-// -*- mode:C++; tab-width:8; c-basic-offset:2; indent-tabs-mode:t -*-
-// vim: ts=8 sw=2 smarttab
-/*
- * Ceph - scalable distributed file system
- *
- * Copyright (C) 2017 OVH
- *
- * This is free software; you can redistribute it and/or
- * modify it under the terms of the GNU Lesser General Public
- * License version 2.1, as published by the Free Software
- * Foundation. See file COPYING.
- *
- */
-
-#ifndef CEPH_COMMON_PERF_HISTOGRAM_H
-#define CEPH_COMMON_PERF_HISTOGRAM_H
-
-#include "common/Formatter.h"
-#include "include/int_types.h"
-
-#include <array>
-#include <atomic>
-#include <memory>
-#include <cassert>
-
-class PerfHistogramCommon {
-public:
- enum scale_type_d : uint8_t {
- SCALE_LINEAR = 1,
- SCALE_LOG2 = 2,
- };
-
- struct axis_config_d {
- const char *m_name = nullptr;
- scale_type_d m_scale_type = SCALE_LINEAR;
- int64_t m_min = 0;
- int64_t m_quant_size = 0;
- int32_t m_buckets = 0;
- axis_config_d() = default;
- axis_config_d(const char* name,
- scale_type_d scale_type,
- int64_t min,
- int64_t quant_size,
- int32_t buckets)
- : m_name(name),
- m_scale_type(scale_type),
- m_min(min),
- m_quant_size(quant_size),
- m_buckets(buckets)
- {}
- };
-
-protected:
- /// Dump configuration of one axis to a formatter
- static void dump_formatted_axis(ceph::Formatter *f, const axis_config_d &ac);
-
- /// Quantize given value and convert to bucket number on given axis
- static int64_t get_bucket_for_axis(int64_t value, const axis_config_d &ac);
-
- /// Calculate inclusive ranges of axis values for each bucket on that axis
- static std::vector<std::pair<int64_t, int64_t>> get_axis_bucket_ranges(
- const axis_config_d &ac);
-};
-
-/// PerfHistogram does trace a histogram of input values. It's an extended
-/// version of a standard histogram which does trace characteristics of a single
-/// one value only. In this implementation, values can be traced in multiple
-/// dimensions - i.e. we can create a histogram of input request size (first
-/// dimension) and processing latency (second dimension). Creating standard
-/// histogram out of such multidimensional one is trivial and requires summing
-/// values across dimensions we're not interested in.
-template <int DIM = 2>
-class PerfHistogram : public PerfHistogramCommon {
-public:
- /// Initialize new histogram object
- PerfHistogram(std::initializer_list<axis_config_d> axes_config) {
- assert(axes_config.size() == DIM &&
- "Invalid number of axis configuration objects");
-
- int i = 0;
- for (const auto &ac : axes_config) {
- assert(ac.m_buckets > 0 && "Must have at least one bucket on axis");
- assert(ac.m_quant_size > 0 &&
- "Quantization unit must be non-zero positive integer value");
-
- m_axes_config[i++] = ac;
- }
-
- m_rawData.reset(new std::atomic<uint64_t>[get_raw_size()]);
- }
-
- /// Copy from other histogram object
- PerfHistogram(const PerfHistogram &other)
- : m_axes_config(other.m_axes_config) {
- int64_t size = get_raw_size();
- m_rawData.reset(new std::atomic<uint64_t>[size]);
- for (int64_t i = 0; i < size; i++) {
- m_rawData[i] = other.m_rawData[i];
- }
- }
-
- /// Set all histogram values to 0
- void reset() {
- auto size = get_raw_size();
- for (auto i = size; --i >= 0;) {
- m_rawData[i] = 0;
- }
- }
-
- /// Increase counter for given axis values by one
- template <typename... T>
- void inc(T... axis) {
- auto index = get_raw_index_for_value(axis...);
- m_rawData[index] += 1;
- }
-
- /// Increase counter for given axis buckets by one
- template <typename... T>
- void inc_bucket(T... bucket) {
- auto index = get_raw_index_for_bucket(bucket...);
- m_rawData[index] += 1;
- }
-
- /// Read value from given bucket
- template <typename... T>
- uint64_t read_bucket(T... bucket) const {
- auto index = get_raw_index_for_bucket(bucket...);
- return m_rawData[index];
- }
-
- /// Dump data to a Formatter object
- void dump_formatted(ceph::Formatter *f) const {
- // Dump axes configuration
- f->open_array_section("axes");
- for (auto &ac : m_axes_config) {
- dump_formatted_axis(f, ac);
- }
- f->close_section();
-
- // Dump histogram values
- dump_formatted_values(f);
- }
-
-protected:
- /// Raw data stored as linear space, internal indexes are calculated on
- /// demand.
- std::unique_ptr<std::atomic<uint64_t>[]> m_rawData;
-
- /// Configuration of axes
- std::array<axis_config_d, DIM> m_axes_config;
-
- /// Dump histogram counters to a formatter
- void dump_formatted_values(ceph::Formatter *f) const {
- visit_values([f](int) { f->open_array_section("values"); },
- [f](int64_t value) { f->dump_unsigned("value", value); },
- [f](int) { f->close_section(); });
- }
-
- /// Get number of all histogram counters
- int64_t get_raw_size() {
- int64_t ret = 1;
- for (const auto &ac : m_axes_config) {
- ret *= ac.m_buckets;
- }
- return ret;
- }
-
- /// Calculate m_rawData index from axis values
- template <typename... T>
- int64_t get_raw_index_for_value(T... axes) const {
- static_assert(sizeof...(T) == DIM, "Incorrect number of arguments");
- return get_raw_index_internal<0>(get_bucket_for_axis, 0, axes...);
- }
-
- /// Calculate m_rawData index from axis bucket numbers
- template <typename... T>
- int64_t get_raw_index_for_bucket(T... buckets) const {
- static_assert(sizeof...(T) == DIM, "Incorrect number of arguments");
- return get_raw_index_internal<0>(
- [](int64_t bucket, const axis_config_d &ac) {
- assert(bucket >= 0 && "Bucket index can not be negative");
- assert(bucket < ac.m_buckets && "Bucket index too large");
- return bucket;
- },
- 0, buckets...);
- }
-
- template <int level = 0, typename F, typename... T>
- int64_t get_raw_index_internal(F bucket_evaluator, int64_t startIndex,
- int64_t value, T... tail) const {
- static_assert(level + 1 + sizeof...(T) == DIM,
- "Internal consistency check");
- auto &ac = m_axes_config[level];
- auto bucket = bucket_evaluator(value, ac);
- return get_raw_index_internal<level + 1>(
- bucket_evaluator, ac.m_buckets * startIndex + bucket, tail...);
- }
-
- template <int level, typename F>
- int64_t get_raw_index_internal(F, int64_t startIndex) const {
- static_assert(level == DIM, "Internal consistency check");
- return startIndex;
- }
-
- /// Visit all histogram counters, call onDimensionEnter / onDimensionLeave
- /// when starting / finishing traversal
- /// on given axis, call onValue when dumping raw histogram counter value.
- template <typename FDE, typename FV, typename FDL>
- void visit_values(FDE onDimensionEnter, FV onValue, FDL onDimensionLeave,
- int level = 0, int startIndex = 0) const {
- if (level == DIM) {
- onValue(m_rawData[startIndex]);
- return;
- }
-
- onDimensionEnter(level);
- auto &ac = m_axes_config[level];
- startIndex *= ac.m_buckets;
- for (int32_t i = 0; i < ac.m_buckets; ++i, ++startIndex) {
- visit_values(onDimensionEnter, onValue, onDimensionLeave, level + 1,
- startIndex);
- }
- onDimensionLeave(level);
- }
-};
-
-#endif
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