QUIC - add UMA histogram to track retransmit rate for large uploads.

net/quic/chromium/quic_chromium_client_session.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/chromium/quic_chromium_client_session.h"
 
 #include <openssl/ssl.h>
 
 #include <utility>
 
@@ skipping 353 matching lines @@
   // (initial values and MTU discovery values), but does not fare well when
   // bucketed.  Because of that, a sparse histogram is used here.
   UMA_HISTOGRAM_SPARSE_SLOWLY("Net.QuicSession.ClientSideMtu",
                               connection()->max_packet_length());
   UMA_HISTOGRAM_SPARSE_SLOWLY("Net.QuicSession.ServerSideMtu",
                               stats.max_received_packet_size);
 
   UMA_HISTOGRAM_COUNTS("Net.QuicSession.MtuProbesSent",
                        connection()->mtu_probe_count());
 
+  if (stats.packets_sent >= 100) {
+    // Used to monitor for regressions that effect large uploads.
+    UMA_HISTOGRAM_COUNTS_1000(
+        "Net.QuicSession.PacketRetransmitsPerMille",
+        1000 * stats.packets_retransmitted / stats.packets_sent);
+  }
+
   if (stats.max_sequence_reordering == 0)
     return;
   const base::HistogramBase::Sample kMaxReordering = 100;
   base::HistogramBase::Sample reordering = kMaxReordering;
   if (stats.min_rtt_us > 0) {
     reordering = static_cast<base::HistogramBase::Sample>(
         100 * stats.max_time_reordering_us / stats.min_rtt_us);
   }
   UMA_HISTOGRAM_CUSTOM_COUNTS("Net.QuicSession.MaxReorderingTime", reordering,
                               1, kMaxReordering, 50);
@@ skipping 1009 matching lines @@
 }
 
 const LoadTimingInfo::ConnectTiming&
 QuicChromiumClientSession::GetConnectTiming() {
   connect_timing_.ssl_start = connect_timing_.connect_start;
   connect_timing_.ssl_end = connect_timing_.connect_end;
   return connect_timing_;
 }
 
 }  // namespace net