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Kernel: Make E1000 sending lockless and mostly non-blocking

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Now we only block if all 256 tx descriptors are waiting to be sent. This
removes TCP acks from taking 30% of profiles while DOWNLOADING files
This commit is contained in:
Bananymous
2026-05-04 21:15:15 +03:00
parent dfe24b69e0
commit 6966475dcf
2 changed files with 21 additions and 17 deletions
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8
kernel/include/kernel/Networking/E1000/E1000.h
View File

@@ -73,11 +73,15 @@ namespace Kernel
BAN::UniqPtr<DMARegion> m_tx_buffer_region;
BAN::UniqPtr<DMARegion> m_rx_descriptor_region;
BAN::UniqPtr<DMARegion> m_tx_descriptor_region;
SpinLock m_lock;
BAN::Atomic<uint32_t> m_tx_head1 { 0 };
BAN::Atomic<uint32_t> m_tx_head2 { 0 };
SpinLock m_rx_lock;
ThreadBlocker m_rx_blocker;
bool m_thread_should_die { false };
BAN::Atomic<bool> m_thread_is_dead { true };
ThreadBlocker m_thread_blocker;
BAN::MACAddress m_mac_address {};
bool m_link_up { false };

28
kernel/kernel/Networking/E1000/E1000.cpp
View File

@@ -59,7 +59,7 @@ namespace Kernel
E1000::~E1000()
{
m_thread_should_die = true;
m_thread_blocker.unblock();
m_rx_blocker.unblock();
while (!m_thread_is_dead)
Processor::yield();
@@ -214,6 +214,7 @@ namespace Kernel
for (size_t i = 0; i < E1000_TX_DESCRIPTOR_COUNT; i++)
{
tx_descriptors[i].addr = m_tx_buffer_region->paddr() + E1000_TX_BUFFER_SIZE * i;
tx_descriptors[i].status = 0xFF; /* NOTE: set status to non-zero so send_bytes doesn't think these are initially pending */
tx_descriptors[i].cmd = 0;
}
@@ -277,9 +278,11 @@ namespace Kernel
BAN::ErrorOr<void> E1000::send_bytes(BAN::MACAddress destination, EtherType protocol, BAN::Span<const BAN::ConstByteSpan> payload)
{
SpinLockGuard _(m_lock);
const uint32_t tx_current = m_tx_head1.fetch_add(1) % E1000_TX_DESCRIPTOR_COUNT;
size_t tx_current = read32(REG_TDT) % E1000_TX_DESCRIPTOR_COUNT;
auto& descriptor = reinterpret_cast<volatile e1000_tx_desc*>(m_tx_descriptor_region->vaddr())[tx_current];
while (descriptor.status == 0)
Processor::yield();
auto* tx_buffer = reinterpret_cast<uint8_t*>(m_tx_buffer_region->vaddr() + E1000_TX_BUFFER_SIZE * tx_current);
@@ -296,15 +299,12 @@ namespace Kernel
packet_size += buffer.size();
}
auto& descriptor = reinterpret_cast<volatile e1000_tx_desc*>(m_tx_descriptor_region->vaddr())[tx_current];
descriptor.length = packet_size;
descriptor.status = 0;
descriptor.cmd = CMD_EOP | CMD_IFCS | CMD_RS;
// FIXME: there isnt really any reason to wait for transmission
if (tx_current == m_tx_head2.fetch_add(1) % E1000_TX_DESCRIPTOR_COUNT)
write32(REG_TDT, (tx_current + 1) % E1000_TX_DESCRIPTOR_COUNT);
while (descriptor.status == 0)
Processor::pause();
dprintln_if(DEBUG_E1000, "sent {} bytes", packet_size);
@@ -313,7 +313,7 @@ namespace Kernel
void E1000::receive_thread()
{
SpinLockGuard _(m_lock);
SpinLockGuard _(m_rx_lock);
while (!m_thread_should_die)
{
@@ -328,21 +328,21 @@ namespace Kernel
dprintln_if(DEBUG_E1000, "got {} bytes", (uint16_t)descriptor.length);
m_lock.unlock(InterruptState::Enabled);
m_rx_lock.unlock(InterruptState::Enabled);
NetworkManager::get().on_receive(*this, BAN::ConstByteSpan {
reinterpret_cast<const uint8_t*>(m_rx_buffer_region->vaddr() + rx_current * E1000_RX_BUFFER_SIZE),
descriptor.length
});
m_lock.lock();
m_rx_lock.lock();
descriptor.status = 0;
write32(REG_RDT0, rx_current);
}
SpinLockAsMutex smutex(m_lock, InterruptState::Enabled);
m_thread_blocker.block_indefinite(&smutex);
SpinLockAsMutex smutex(m_rx_lock, InterruptState::Enabled);
m_rx_blocker.block_indefinite(&smutex);
}
m_thread_is_dead = true;
@@ -355,8 +355,8 @@ namespace Kernel
if (icr & (ICR_RxQ0 | ICR_RXT0))
{
SpinLockGuard _(m_lock);
m_thread_blocker.unblock();
SpinLockGuard _(m_rx_lock);
m_rx_blocker.unblock();
}
}