profcollectd/libprofcollectd/trace_provider/simpleperf_lbr.rs

//
// Copyright (C) 2023 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.
//

//! Trace provider backed by Intel LBR, using simpleperf tool.
use anyhow::{anyhow, Result};
use std::fs::{read_dir, remove_file};
use std::path::{Path, PathBuf};
use std::time::Duration;
use trace_provider::TraceProvider;

use crate::trace_provider;

static LBR_TRACEFILE_EXTENSION: &str = "lbrtrace";
static LBR_PROFILE_EXTENSION: &str = "data";
// Use a prime value to make sure that there are no weird interactions with e.g. short loops.
static LBR_SAMPLE_PERIOD: &str = "500009";

pub struct SimpleperfLbrTraceProvider {}

impl TraceProvider for SimpleperfLbrTraceProvider {
    fn get_name(&self) -> &'static str {
        "simpleperf_lbr"
    }

    fn is_ready(&self) -> bool {
        true
    }

    fn trace_system(
        &self,
        trace_dir: &Path,
        tag: &str,
        sampling_period: &Duration,
        binary_filter: &str,
    ) {
        let trace_file = trace_provider::get_path(trace_dir, tag, LBR_TRACEFILE_EXTENSION);
        // Record ETM data for kernel space only when it's not filtered out by binary_filter. So we
        // can get more ETM data for user space when ETM data for kernel space isn't needed.
        let event_name = if binary_filter.contains("kernel") {
            "BR_INST_RETIRED.NEAR_TAKEN"
        } else {
            "BR_INST_RETIRED.NEAR_TAKEN:u"
        };
        let duration: String = sampling_period.as_secs_f64().to_string();
        let args: Vec<&str> = vec![
            "-a",
            "-e",
            event_name,
            "-c",
            LBR_SAMPLE_PERIOD,
            "--duration",
            &duration,
            "-b",
            "--exclude-perf",
            "--binary",
            binary_filter,
            "--no-dump-symbols",
            "--no-dump-kernel-symbols",
            "-o",
            trace_file.to_str().unwrap(),
        ];
        simpleperf_profcollect::run_record_cmd(&args);
    }

    fn trace_process(
        &self,
        trace_dir: &Path,
        tag: &str,
        sampling_period: &Duration,
        processes: &str,
    ) {
        let trace_file = trace_provider::get_path(trace_dir, tag, LBR_TRACEFILE_EXTENSION);
        let event_name = "BR_INST_RETIRED.NEAR_TAKEN:u";
        let duration: String = sampling_period.as_secs_f64().to_string();
        let args: Vec<&str> = vec![
            "-p",
            processes,
            "-e",
            event_name,
            "-c",
            LBR_SAMPLE_PERIOD,
            "--duration",
            &duration,
            "-b",
            "--no-dump-symbols",
            "-o",
            trace_file.to_str().unwrap(),
        ];
        simpleperf_profcollect::run_record_cmd(&args);
    }

    fn process(&self, trace_dir: &Path, profile_dir: &Path, binary_filter: &str) -> Result<()> {
        let is_lbr_extension = |file: &PathBuf| {
            file.extension()
                .and_then(|f| f.to_str())
                .filter(|ext| ext == &LBR_TRACEFILE_EXTENSION)
                .is_some()
        };

        let process_trace_file = |trace_file: PathBuf| {
            let mut profile_file = PathBuf::from(profile_dir);
            profile_file.push(
                trace_file
                    .file_name()
                    .ok_or_else(|| anyhow!("Malformed trace path: {}", trace_file.display()))?,
            );
            profile_file.set_extension(LBR_PROFILE_EXTENSION);

            let args: Vec<&str> = vec![
                "-i",
                trace_file.to_str().unwrap(),
                "-o",
                profile_file.to_str().unwrap(),
                "--output",
                "branch-list",
                "--binary",
                binary_filter,
            ];
            simpleperf_profcollect::run_inject_cmd(&args);
            remove_file(&trace_file)?;
            Ok(())
        };

        read_dir(trace_dir)?
            .filter_map(|e| e.ok())
            .map(|e| e.path())
            .filter(|e| e.is_file())
            .filter(is_lbr_extension)
            .try_for_each(process_trace_file)
    }

    fn set_log_file(&self, filename: &Path) {
        simpleperf_profcollect::set_log_file(filename);
    }

    fn reset_log_file(&self) {
        simpleperf_profcollect::reset_log_file();
    }
}

impl SimpleperfLbrTraceProvider {
    pub fn supported() -> bool {
        simpleperf_profcollect::is_lbr_available()
    }
}