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/*
* Copyright (C) 2020 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include "src/profiling/perf/event_config.h"
#include <linux/perf_event.h>
#include <time.h>
#include <unwindstack/Regs.h>
#include "perfetto/base/flat_set.h"
#include "perfetto/ext/base/optional.h"
#include "perfetto/profiling/normalize.h"
#include "src/profiling/perf/regs_parsing.h"
#include "protos/perfetto/config/profiling/perf_event_config.pbzero.h"
namespace perfetto {
namespace profiling {
namespace {
constexpr uint64_t kDefaultSamplingFrequencyHz = 10;
constexpr uint32_t kDefaultDataPagesPerRingBuffer = 256; // 1 MB: 256x 4k pages
constexpr uint32_t kDefaultReadTickPeriodMs = 100;
constexpr uint32_t kDefaultRemoteDescriptorTimeoutMs = 100;
base::Optional<std::string> Normalize(const protozero::ConstChars& src) {
// Construct a null-terminated string that will be mutated by the normalizer.
std::vector<char> base(src.size + 1);
memcpy(base.data(), src.data, src.size);
base[src.size] = '\0';
char* new_start = base.data();
ssize_t new_sz = NormalizeCmdLine(&new_start, base.size());
if (new_sz < 0) {
PERFETTO_ELOG("Failed to normalize config cmdline [%s], aborting",
base.data());
return base::nullopt;
}
return base::make_optional<std::string>(new_start,
static_cast<size_t>(new_sz));
}
// returns |base::nullopt| if any of the input cmdlines couldn't be normalized.
base::Optional<TargetFilter> ParseTargetFilter(
const protos::pbzero::PerfEventConfig::Decoder& cfg) {
TargetFilter filter;
for (auto it = cfg.target_cmdline(); it; ++it) {
base::Optional<std::string> opt = Normalize(*it);
if (!opt.has_value())
return base::nullopt;
filter.cmdlines.insert(std::move(opt.value()));
}
for (auto it = cfg.exclude_cmdline(); it; ++it) {
base::Optional<std::string> opt = Normalize(*it);
if (!opt.has_value())
return base::nullopt;
filter.exclude_cmdlines.insert(std::move(opt.value()));
}
for (auto it = cfg.target_pid(); it; ++it) {
filter.pids.insert(*it);
}
for (auto it = cfg.exclude_pid(); it; ++it) {
filter.exclude_pids.insert(*it);
}
return base::make_optional(std::move(filter));
}
constexpr bool IsPowerOfTwo(size_t v) {
return (v != 0 && ((v & (v - 1)) == 0));
}
// returns |base::nullopt| if the input is invalid.
base::Optional<uint32_t> ChooseActualRingBufferPages(uint32_t config_value) {
if (!config_value) {
static_assert(IsPowerOfTwo(kDefaultDataPagesPerRingBuffer), "");
return base::make_optional(kDefaultDataPagesPerRingBuffer);
}
if (!IsPowerOfTwo(config_value)) {
PERFETTO_ELOG("kernel buffer size must be a power of two pages");
return base::nullopt;
}
return base::make_optional(config_value);
}
} // namespace
// static
base::Optional<EventConfig> EventConfig::Create(
const DataSourceConfig& ds_config) {
protos::pbzero::PerfEventConfig::Decoder pb_config(
ds_config.perf_event_config_raw());
base::Optional<TargetFilter> filter = ParseTargetFilter(pb_config);
if (!filter.has_value())
return base::nullopt;
base::Optional<uint32_t> ring_buffer_pages =
ChooseActualRingBufferPages(pb_config.ring_buffer_pages());
if (!ring_buffer_pages.has_value())
return base::nullopt;
uint32_t remote_descriptor_timeout_ms =
pb_config.remote_descriptor_timeout_ms()
? pb_config.remote_descriptor_timeout_ms()
: kDefaultRemoteDescriptorTimeoutMs;
uint32_t read_tick_period_ms = pb_config.ring_buffer_read_period_ms()
? pb_config.ring_buffer_read_period_ms()
: kDefaultReadTickPeriodMs;
uint32_t sampling_frequency = pb_config.sampling_frequency()
? pb_config.sampling_frequency()
: kDefaultSamplingFrequencyHz;
// Take the ratio of sampling and reading frequencies, which gives the
// upper bound on number of samples per tick (for a single per-cpu buffer).
// Overflow not a concern for sane inputs.
uint32_t expected_samples_per_tick =
1 + (sampling_frequency * read_tick_period_ms) / 1000;
// Use double the expected value as the actual guardrail (don't assume that
// periodic read task is as exact as the kernel).
uint32_t samples_per_tick_limit = 2 * expected_samples_per_tick;
PERFETTO_DCHECK(samples_per_tick_limit > 0);
PERFETTO_DLOG("Capping samples (not records) per tick to [%" PRIu32 "]",
samples_per_tick_limit);
return EventConfig(pb_config, sampling_frequency, ring_buffer_pages.value(),
read_tick_period_ms, samples_per_tick_limit,
remote_descriptor_timeout_ms, std::move(filter.value()));
}
EventConfig::EventConfig(const protos::pbzero::PerfEventConfig::Decoder& cfg,
uint32_t sampling_frequency,
uint32_t ring_buffer_pages,
uint32_t read_tick_period_ms,
uint32_t samples_per_tick_limit,
uint32_t remote_descriptor_timeout_ms,
TargetFilter target_filter)
: target_all_cpus_(cfg.all_cpus()),
ring_buffer_pages_(ring_buffer_pages),
read_tick_period_ms_(read_tick_period_ms),
samples_per_tick_limit_(samples_per_tick_limit),
target_filter_(std::move(target_filter)),
remote_descriptor_timeout_ms_(remote_descriptor_timeout_ms),
unwind_state_clear_period_ms_(cfg.unwind_state_clear_period_ms()) {
auto& pe = perf_event_attr_;
pe.size = sizeof(perf_event_attr);
pe.disabled = false;
// Ask the kernel to sample at a given frequency.
pe.type = PERF_TYPE_SOFTWARE;
pe.config = PERF_COUNT_SW_CPU_CLOCK;
pe.freq = true;
pe.sample_freq = sampling_frequency;
pe.sample_type = PERF_SAMPLE_TID | PERF_SAMPLE_TIME | PERF_SAMPLE_STACK_USER |
PERF_SAMPLE_REGS_USER;
// PERF_SAMPLE_TIME:
pe.clockid = CLOCK_BOOTTIME;
pe.use_clockid = true;
// PERF_SAMPLE_STACK_USER:
// Needs to be < ((u16)(~0u)), and have bottom 8 bits clear.
pe.sample_stack_user = (1u << 15);
// PERF_SAMPLE_REGS_USER:
pe.sample_regs_user =
PerfUserRegsMaskForArch(unwindstack::Regs::CurrentArch());
}
} // namespace profiling
} // namespace perfetto
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