relnote: Cache-align the encryption buffer in QuicPacketGenerator::SerializeAndSendPacket.

net/quic/quic_packet_generator.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "net/quic/quic_packet_generator.h"
 
 #include "base/basictypes.h"
 #include "base/logging.h"
 #include "net/quic/quic_ack_notifier.h"
 #include "net/quic/quic_fec_group.h"
@@ skipping 436 matching lines @@
   bool success = needs_padding
                      ? packet_creator_.AddPaddedSavedFrame(frame, buffer)
                      : packet_creator_.AddSavedFrame(frame, buffer);
   if (success && debug_delegate_) {
     debug_delegate_->OnFrameAddedToPacket(frame);
   }
   return success;
 }
 
 void QuicPacketGenerator::SerializeAndSendPacket() {
-  char buffer[kMaxPacketSize];
+  // The optimized encryption algorithm implementations run faster when
+  // operating on aligned memory.
+  //
+  // TODO(rtenneti): Change the default 64 alignas value (used the default
+  // value from CACHELINE_SIZE).
+  ALIGNAS(64) char buffer[kMaxPacketSize];
   SerializedPacket serialized_packet =
       packet_creator_.SerializePacket(buffer, kMaxPacketSize);
   if (serialized_packet.packet == nullptr) {
     LOG(DFATAL) << "Failed to SerializePacket. fec_policy:" << fec_send_policy_
                 << " should_fec_protect_:" << should_fec_protect_;
     delegate_->CloseConnection(QUIC_FAILED_TO_SERIALIZE_PACKET, false);
     return;
   }
 
   // There may be AckNotifiers interested in this packet.
@@ skipping 82 matching lines @@
 void QuicPacketGenerator::set_encryption_level(EncryptionLevel level) {
   packet_creator_.set_encryption_level(level);
 }
 
 void QuicPacketGenerator::SetEncrypter(EncryptionLevel level,
                                        QuicEncrypter* encrypter) {
   packet_creator_.SetEncrypter(level, encrypter);
 }
 
 }  // namespace net