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78 lines
3.2 KiB
C++
78 lines
3.2 KiB
C++
/*
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* Copyright (c) 2024, Andrew Kaster <akaster@serenityos.org>
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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#include <AK/String.h>
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#include <LibCore/File.h>
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#include <LibCore/Platform/ProcessStatistics.h>
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#include <unistd.h>
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namespace Core::Platform {
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static auto user_hz = sysconf(_SC_CLK_TCK);
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static auto page_size = sysconf(_SC_PAGESIZE);
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static auto ncpu_online = sysconf(_SC_NPROCESSORS_ONLN);
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ErrorOr<void> update_process_statistics(ProcessStatistics& statistics)
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{
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// Read the total time scheduled from /proc/stat, and each process's usage from /proc/pid/stat
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// Calculate the CPU percentage for each process based on the total time scheduled and the time spent in the process
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static auto proc_stat = TRY(Core::File::open("/proc/stat"sv, Core::File::OpenMode::Read));
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TRY(proc_stat->seek(0, SeekMode::SetPosition));
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char buf[1024] = {};
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auto buffer = Bytes { buf, sizeof(buf) };
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auto line = TRY(proc_stat->read_some(buffer));
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int user_time = 0;
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int system_time = 0;
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int idle_time = 0;
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int irq_time = 0;
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int softirq_time = 0;
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// user, nice (ignored), system, idle, iowait (ignored), irq, softirq, steal (ignored), guest (ignored), guest_nice (ignored)
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int res = sscanf(reinterpret_cast<char const*>(line.data()), "cpu %d %*d %d %d %*d %d %d", &user_time, &system_time, &idle_time, &irq_time, &softirq_time);
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if (res != 5)
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return Error::from_string_literal("Failed to parse /proc/stat");
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u64 const total_time_scheduled = user_time + system_time + idle_time + irq_time + softirq_time;
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float const total_time_scheduled_diff = total_time_scheduled - statistics.total_time_scheduled;
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statistics.total_time_scheduled = total_time_scheduled;
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for (auto& process : statistics.processes) {
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auto proc_pid_stat_or_error = Core::File::open(MUST(String::formatted("/proc/{}/stat", process->pid)), Core::File::OpenMode::Read);
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if (proc_pid_stat_or_error.is_error()) {
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// FIXME: Remove stale process from process list?
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continue;
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}
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auto proc_pid_stat = proc_pid_stat_or_error.release_value();
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line = TRY(proc_pid_stat->read_some(buffer));
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// We only care about fields 14 (utime), 15 (stime), and 24 (rss)
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unsigned long utime = 0;
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unsigned long stime = 0;
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long rss = 0;
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// 1 2 3 4 5 6 7 8 9 10 11 12 13 14* 15* 16 17 18 19 20 21 22 23 24*
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res = sscanf(reinterpret_cast<char const*>(line.data()), "%*d %*s %*c %*d %*d %*d %*d %*d %*u %*u %*u %*u %*u %lu %lu %*d %*d %*d %*d %*d %*d %*u %*u %ld", &utime, &stime, &rss);
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if (res != 3)
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return Error::from_string_literal("Failed to parse /proc/pid/stat");
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process->memory_usage_bytes = rss * page_size;
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u64 const time_process = utime + stime;
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float const time_scheduled_diff = time_process - process->time_spent_in_process;
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process->time_spent_in_process = time_process;
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process->cpu_percent = 0.0;
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if (total_time_scheduled_diff > 0) {
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process->cpu_percent = time_scheduled_diff / (total_time_scheduled_diff / ncpu_online) * 100.0f;
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}
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}
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return {};
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}
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}
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