Kernel: Rewrite the whole scheduler and re-architecture SMP handling

Change Semaphore -> ThreadBlocker
  This was not a semaphore, I just named it one because I didn't know
  what semaphore was. I have meant to change this sooner, but it was in
  no way urgent :D

Implement SMP events. Processors can now be sent SMP events through
IPIs. SMP events can be sent either to a single processor or broadcasted
to every processor.

PageTable::{map_page,map_range,unmap_page,unmap_range}() now send SMP
event to invalidate TLB caches for the changed pages.

Scheduler no longer uses a global run queue. Each processor has its own
scheduler that keeps track of the load on the processor. Once every
second schedulers do load balancing. Schedulers have no access to other
processors' schedulers, they just see approximate loads. If scheduler
decides that it has too much load, it will send a thread to another
processor through a SMP event.

Schedulers are currently run using the timer interrupt on BSB. This
should be not the case, and each processor should use its LAPIC timer
for interrupts. There is no reason to broadcast SMP event to all
processors when BSB gets timer interrupt.

Old scheduler only achieved 20% idle load on qemu. That was probably a
very inefficient implementation. This new scheduler seems to average
around 1% idle load. This is much closer to what I would expect. On my
own laptop idle load seems to be only around 0.5% on each processor.

kernel/kernel/Networking/ARPTable.cpp

@@ -79,7 +79,7 @@ namespace Kernel
 				if (it != m_arp_table.end())
 					return it->value;
 			}
-			Scheduler::get().yield();
+			Processor::yield();
 		}
 
 		return BAN::Error::from_errno(ETIMEDOUT);
@@ -150,7 +150,7 @@ namespace Kernel
 				while (m_pending_packets.empty())
 				{
 					m_pending_lock.unlock(state);
-					m_pending_semaphore.block_indefinite();
+					m_pending_thread_blocker.block_indefinite();
 					state = m_pending_lock.lock();
 				}
 				auto packet = m_pending_packets.front();
@@ -178,7 +178,7 @@ namespace Kernel
 		}
 
 		m_pending_packets.push({ .interface = interface, .packet = arp_packet });
-		m_pending_semaphore.unblock();
+		m_pending_thread_blocker.unblock();
 	}
 
 }

kernel/kernel/Networking/IPv4Layer.cpp

@@ -308,7 +308,7 @@ namespace Kernel
 				while (m_pending_packets.empty())
 				{
 					m_pending_lock.unlock(state);
-					m_pending_semaphore.block_indefinite();
+					m_pending_thread_blocker.block_indefinite();
 					state = m_pending_lock.lock();
 				}
 				auto packet = m_pending_packets.front();
@@ -367,7 +367,7 @@ namespace Kernel
 		m_pending_total_size += ipv4_header.total_length;
 
 		m_pending_packets.push({ .interface = interface });
-		m_pending_semaphore.unblock();
+		m_pending_thread_blocker.unblock();
 	}
 
 }

kernel/kernel/Networking/TCPSocket.cpp

@@ -75,7 +75,7 @@ namespace Kernel
 		while (m_pending_connections.empty())
 		{
 			LockFreeGuard _(m_mutex);
-			TRY(Thread::current().block_or_eintr_indefinite(m_semaphore));
+			TRY(Thread::current().block_or_eintr_indefinite(m_thread_blocker));
 		}
 
 		auto connection = m_pending_connections.front();
@@ -113,7 +113,7 @@ namespace Kernel
 			if (SystemTimer::get().ms_since_boot() >= wake_time_ms)
 				return BAN::Error::from_errno(ECONNABORTED);
 			LockFreeGuard free(m_mutex);
-			TRY(Thread::current().block_or_eintr_or_waketime(return_inode->m_semaphore, wake_time_ms, true));
+			TRY(Thread::current().block_or_eintr_or_waketime_ms(return_inode->m_thread_blocker, wake_time_ms, true));
 		}
 
 		if (address)
@@ -170,7 +170,7 @@ namespace Kernel
 			if (SystemTimer::get().ms_since_boot() >= wake_time_ms)
 				return BAN::Error::from_errno(ECONNREFUSED);
 			LockFreeGuard free(m_mutex);
-			TRY(Thread::current().block_or_eintr_or_waketime(m_semaphore, wake_time_ms, true));
+			TRY(Thread::current().block_or_eintr_or_waketime_ms(m_thread_blocker, wake_time_ms, true));
 		}
 
 		return {};
@@ -207,7 +207,7 @@ namespace Kernel
 			if (m_state != State::Established)
 				return return_with_maybe_zero();
 			LockFreeGuard free(m_mutex);
-			TRY(Thread::current().block_or_eintr_indefinite(m_semaphore));
+			TRY(Thread::current().block_or_eintr_indefinite(m_thread_blocker));
 		}
 
 		const uint32_t to_recv = BAN::Math::min<uint32_t>(buffer.size(), m_recv_window.data_size);
@@ -249,7 +249,7 @@ namespace Kernel
 			if (m_send_window.data_size + message.size() <= m_send_window.buffer->size())
 				break;
 			LockFreeGuard free(m_mutex);
-			TRY(Thread::current().block_or_eintr_indefinite(m_semaphore));
+			TRY(Thread::current().block_or_eintr_indefinite(m_thread_blocker));
 		}
 
 		{
@@ -259,14 +259,14 @@ namespace Kernel
 		}
 
 		const uint32_t target_ack = m_send_window.start_seq + m_send_window.data_size;
-		m_semaphore.unblock();
+		m_thread_blocker.unblock();
 
 		while (m_send_window.current_ack < target_ack)
 		{
 			if (m_state != State::Established)
 				return return_with_maybe_zero();
 			LockFreeGuard free(m_mutex);
-			TRY(Thread::current().block_or_eintr_indefinite(m_semaphore));
+			TRY(Thread::current().block_or_eintr_indefinite(m_thread_blocker));
 		}
 
 		return message.size();
@@ -597,7 +597,7 @@ namespace Kernel
 			}
 		}
 
-		m_semaphore.unblock();
+		m_thread_blocker.unblock();
 	}
 
 	void TCPSocket::set_connection_as_closed()
@@ -743,11 +743,11 @@ namespace Kernel
 				}
 			}
 
-			m_semaphore.unblock();
-			m_semaphore.block_with_wake_time(current_ms + retransmit_timeout_ms);
+			m_thread_blocker.unblock();
+			m_thread_blocker.block_with_wake_time_ms(current_ms + retransmit_timeout_ms);
 		}
 
-		m_semaphore.unblock();
+		m_thread_blocker.unblock();
 	}
 
 }

kernel/kernel/Networking/UDPSocket.cpp

@@ -70,7 +70,7 @@ namespace Kernel
 		m_packets.emplace(packet_info);
 		m_packet_total_size += payload.size();
 
-		m_packet_semaphore.unblock();
+		m_packet_thread_blocker.unblock();
 	}
 
 	BAN::ErrorOr<void> UDPSocket::bind_impl(const sockaddr* address, socklen_t address_len)
@@ -93,7 +93,7 @@ namespace Kernel
 		while (m_packets.empty())
 		{
 			m_packet_lock.unlock(state);
-			TRY(Thread::current().block_or_eintr_indefinite(m_packet_semaphore));
+			TRY(Thread::current().block_or_eintr_indefinite(m_packet_thread_blocker));
 			state = m_packet_lock.lock();
 		}
 

kernel/kernel/Networking/UNIX/Socket.cpp

@@ -73,7 +73,7 @@ namespace Kernel
 			return BAN::Error::from_errno(EINVAL);
 
 		while (connection_info.pending_connections.empty())
-			TRY(Thread::current().block_or_eintr_indefinite(connection_info.pending_semaphore));
+			TRY(Thread::current().block_or_eintr_indefinite(connection_info.pending_thread_blocker));
 
 		BAN::RefPtr<UnixDomainSocket> pending;
 
@@ -81,7 +81,7 @@ namespace Kernel
 			SpinLockGuard _(connection_info.pending_lock);
 			pending = connection_info.pending_connections.front();
 			connection_info.pending_connections.pop();
-			connection_info.pending_semaphore.unblock();
+			connection_info.pending_thread_blocker.unblock();
 		}
 
 		BAN::RefPtr<UnixDomainSocket> return_inode;
@@ -162,15 +162,15 @@ namespace Kernel
 				if (target_info.pending_connections.size() < target_info.pending_connections.capacity())
 				{
 					MUST(target_info.pending_connections.push(this));
-					target_info.pending_semaphore.unblock();
+					target_info.pending_thread_blocker.unblock();
 					break;
 				}
 			}
-			TRY(Thread::current().block_or_eintr_indefinite(target_info.pending_semaphore));
+			TRY(Thread::current().block_or_eintr_indefinite(target_info.pending_thread_blocker));
 		}
 
 		while (!connection_info.connection_done)
-			Scheduler::get().yield();
+			Processor::yield();
 
 		return {};
 	}
@@ -241,7 +241,7 @@ namespace Kernel
 		while (m_packet_sizes.full() || m_packet_size_total + packet.size() > s_packet_buffer_size)
 		{
 			m_packet_lock.unlock(state);
-			TRY(Thread::current().block_or_eintr_indefinite(m_packet_semaphore));
+			TRY(Thread::current().block_or_eintr_indefinite(m_packet_thread_blocker));
 			state = m_packet_lock.lock();
 		}
 
@@ -252,7 +252,7 @@ namespace Kernel
 		if (!is_streaming())
 			m_packet_sizes.push(packet.size());
 
-		m_packet_semaphore.unblock();
+		m_packet_thread_blocker.unblock();
 		m_packet_lock.unlock(state);
 		return {};
 	}
@@ -357,7 +357,7 @@ namespace Kernel
 		while (m_packet_size_total == 0)
 		{
 			m_packet_lock.unlock(state);
-			TRY(Thread::current().block_or_eintr_indefinite(m_packet_semaphore));
+			TRY(Thread::current().block_or_eintr_indefinite(m_packet_thread_blocker));
 			state = m_packet_lock.lock();
 		}
 
@@ -376,7 +376,7 @@ namespace Kernel
 		memmove(packet_buffer, packet_buffer + nread, m_packet_size_total - nread);
 		m_packet_size_total -= nread;
 
-		m_packet_semaphore.unblock();
+		m_packet_thread_blocker.unblock();
 		m_packet_lock.unlock(state);
 
 		return nread;