ladybird/Userland/top.cpp
Andreas Kling 50677bf806 Kernel: Refactor scheduler to use dynamic thread priorities
Threads now have numeric priorities with a base priority in the 1-99
range.

Whenever a runnable thread is *not* scheduled, its effective priority
is incremented by 1. This is tracked in Thread::m_extra_priority.
The effective priority of a thread is m_priority + m_extra_priority.

When a runnable thread *is* scheduled, its m_extra_priority is reset to
zero and the effective priority returns to base.

This means that lower-priority threads will always eventually get
scheduled to run, once its effective priority becomes high enough to
exceed the base priority of threads "above" it.

The previous values for ThreadPriority (Low, Normal and High) are now
replaced as follows:

    Low -> 10
    Normal -> 30
    High -> 50

In other words, it will take 20 ticks for a "Low" priority thread to
get to "Normal" effective priority, and another 20 to reach "High".

This is not perfect, and I've used some quite naive data structures,
but I think the mechanism will allow us to build various new and
interesting optimizations, and we can figure out better data structures
later on. :^)
2019-12-30 18:46:17 +01:00

166 lines
5 KiB
C++

#include <AK/HashMap.h>
#include <AK/JsonArray.h>
#include <AK/JsonObject.h>
#include <AK/JsonValue.h>
#include <AK/QuickSort.h>
#include <AK/String.h>
#include <AK/Vector.h>
#include <LibCore/CProcessStatisticsReader.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
struct ThreadData {
int tid;
pid_t pid;
unsigned pgid;
unsigned pgp;
unsigned sid;
uid_t uid;
gid_t gid;
pid_t ppid;
unsigned nfds;
String name;
String tty;
size_t amount_virtual;
size_t amount_resident;
size_t amount_shared;
unsigned syscall_count;
unsigned inode_faults;
unsigned zero_faults;
unsigned cow_faults;
int icon_id;
unsigned times_scheduled;
unsigned times_scheduled_since_prev { 0 };
unsigned cpu_percent { 0 };
unsigned cpu_percent_decimal { 0 };
u32 priority;
String username;
String state;
};
struct PidAndTid {
bool operator==(const PidAndTid& other) const
{
return pid == other.pid && tid == other.tid;
}
pid_t pid;
int tid;
};
namespace AK {
template<>
struct Traits<PidAndTid> : public GenericTraits<PidAndTid> {
static unsigned hash(const PidAndTid& value) { return pair_int_hash(value.pid, value.tid); }
};
}
struct Snapshot {
HashMap<PidAndTid, ThreadData> map;
u32 sum_times_scheduled { 0 };
};
static Snapshot get_snapshot()
{
Snapshot snapshot;
auto all_processes = CProcessStatisticsReader::get_all();
for (auto& it : all_processes) {
auto& stats = it.value;
for (auto& thread : stats.threads) {
snapshot.sum_times_scheduled += thread.times_scheduled;
ThreadData thread_data;
thread_data.tid = thread.tid;
thread_data.pid = stats.pid;
thread_data.pgid = stats.pgid;
thread_data.pgp = stats.pgp;
thread_data.sid = stats.sid;
thread_data.uid = stats.uid;
thread_data.gid = stats.gid;
thread_data.ppid = stats.ppid;
thread_data.nfds = stats.nfds;
thread_data.name = stats.name;
thread_data.tty = stats.tty;
thread_data.amount_virtual = stats.amount_virtual;
thread_data.amount_resident = stats.amount_resident;
thread_data.amount_shared = stats.amount_shared;
thread_data.syscall_count = thread.syscall_count;
thread_data.inode_faults = thread.inode_faults;
thread_data.zero_faults = thread.zero_faults;
thread_data.cow_faults = thread.cow_faults;
thread_data.icon_id = stats.icon_id;
thread_data.times_scheduled = thread.times_scheduled;
thread_data.priority = thread.priority;
thread_data.state = thread.state;
thread_data.username = stats.username;
snapshot.map.set({ stats.pid, thread.tid }, move(thread_data));
}
}
return snapshot;
}
int main(int, char**)
{
Vector<ThreadData*> threads;
auto prev = get_snapshot();
usleep(10000);
for (;;) {
auto current = get_snapshot();
auto sum_diff = current.sum_times_scheduled - prev.sum_times_scheduled;
printf("\033[3J\033[H\033[2J");
printf("\033[47;30m%6s %3s %3s %-8s %-10s %6s %6s %4s %s\033[K\033[0m\n",
"PID",
"TID",
"PRI",
"USER",
"STATE",
"VIRT",
"PHYS",
"%CPU",
"NAME");
for (auto& it : current.map) {
auto pid_and_tid = it.key;
if (pid_and_tid.pid == 0)
continue;
u32 times_scheduled_now = it.value.times_scheduled;
auto jt = prev.map.find(pid_and_tid);
if (jt == prev.map.end())
continue;
u32 times_scheduled_before = (*jt).value.times_scheduled;
u32 times_scheduled_diff = times_scheduled_now - times_scheduled_before;
it.value.times_scheduled_since_prev = times_scheduled_diff;
it.value.cpu_percent = ((times_scheduled_diff * 100) / sum_diff);
it.value.cpu_percent_decimal = (((times_scheduled_diff * 1000) / sum_diff) % 10);
threads.append(&it.value);
}
quick_sort(threads.begin(), threads.end(), [](auto* p1, auto* p2) {
return p2->times_scheduled_since_prev < p1->times_scheduled_since_prev;
});
for (auto* thread : threads) {
printf("%6d %3d %2u %-8s %-10s %6zu %6zu %2u.%1u %s\n",
thread->pid,
thread->tid,
thread->priority,
thread->username.characters(),
thread->state.characters(),
thread->amount_virtual / 1024,
thread->amount_resident / 1024,
thread->cpu_percent,
thread->cpu_percent_decimal,
thread->name.characters());
}
threads.clear_with_capacity();
prev = move(current);
sleep(1);
}
return 0;
}