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Kernel: Avoid allocations when receiving network packets

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This avoids two allocations when receiving network packets. One for
inserting a PacketWithTimestamp into m_packet_queue and another one
when inserting buffers into the list of unused packet buffers.

With this fixed the only allocations in NetworkTask happen when
initially allocating the PacketWithTimestamp structs and when switching
contexts.
This commit is contained in:
Gunnar Beutner 2021-05-14 09:52:49 +02:00 • committed by Andreas Kling
parent b66f91e7d3
commit 093818de62
2 changed files with 37 additions and 23 deletions
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40
Kernel/Net/NetworkAdapter.cpp
View file

@ -153,27 +153,34 @@ void NetworkAdapter::did_receive(ReadonlyBytes payload)
m_packets_in++;
m_bytes_in += payload.size();
Optional<KBuffer> buffer;
if (m_packet_queue_size == max_packet_buffers) {
// FIXME: Keep track of the number of dropped packets
return;
}
if (m_unused_packet_buffers.is_empty()) {
buffer = KBuffer::copy(payload.data(), payload.size());
RefPtr<PacketWithTimestamp> packet;
if (m_unused_packets.is_empty()) {
auto buffer = KBuffer::copy(payload.data(), payload.size());
packet = adopt_ref_if_nonnull(new PacketWithTimestamp { move(buffer), kgettimeofday() });
} else {
buffer = m_unused_packet_buffers.take_first();
--m_unused_packet_buffers_count;
if (payload.size() <= buffer.value().capacity()) {
memcpy(buffer.value().data(), payload.data(), payload.size());
buffer.value().set_size(payload.size());
packet = m_unused_packets.take_first();
if (payload.size() <= packet->buffer.capacity()) {
memcpy(packet->buffer.data(), payload.data(), payload.size());
packet->buffer.set_size(payload.size());
packet->timestamp = kgettimeofday();
} else {
buffer = KBuffer::copy(payload.data(), payload.size());
auto buffer = KBuffer::copy(payload.data(), payload.size());
packet = adopt_ref_if_nonnull(new PacketWithTimestamp { move(buffer), kgettimeofday() });
}
}
m_packet_queue.append({ buffer.value(), kgettimeofday() });
if (!packet) {
dbgln("Discarding packet because we're out of memory");
return;
}
m_packet_queue.append(*packet);
m_packet_queue_size++;
if (on_receive)
@ -187,13 +194,12 @@ size_t NetworkAdapter::dequeue_packet(u8* buffer, size_t buffer_size, Time& pack
return 0;
auto packet_with_timestamp = m_packet_queue.take_first();
m_packet_queue_size--;
packet_timestamp = packet_with_timestamp.timestamp;
auto packet = move(packet_with_timestamp.packet);
size_t packet_size = packet.size();
packet_timestamp = packet_with_timestamp->timestamp;
auto& packet_buffer = packet_with_timestamp->buffer;
size_t packet_size = packet_buffer.size();
VERIFY(packet_size <= buffer_size);
memcpy(buffer, packet.data(), packet_size);
m_unused_packet_buffers.append(packet);
++m_unused_packet_buffers_count;
memcpy(buffer, packet_buffer.data(), packet_size);
m_unused_packets.append(*packet_with_timestamp);
return packet_size;
}