commit 12af6f73218ed3e047527aa83f95387da962d071
author Steven Moreland <smoreland@google.com> Tue Mar 07 15:14:25 2023 +0000
committer Steven Moreland <smoreland@google.com> Tue Mar 07 16:46:24 2023 +0000
tree 8ae6f20c251dc5d9c6c6ed96e76c5720eb4bf7de
parent 65fac116d3e2551023f2d5c39ffeaa0e6f33a563

RPC Binder: disable Nagle's algorithm

For some reason, I thought we did this - I thought it was
incidental to some other API we used. RPC Binder is an RPC
system, AND ONE WITH SYNCHRONOUS CALLS! It should not hold
these packets.

Bug: 271860373
Test: run inet cases before/after:
    binderRpcTest --gtest_filter="*PerSocket/BinderRpc.RepeatBinderNull/inet_socket_tls_clientV0_serverV4026531840_single_threaded_no_kernel*"
    before: 0m26.845s
    after: 0m12.271s

Change-Id: Ib257b53cd2e4ca19041cdb5fd985be346e3fac5e

libs/binder/RpcSession.cpp

diff --git a/libs/binder/RpcSession.cpp b/libs/binder/RpcSession.cpp
index 1a821f1..bba0bcb 100644
--- a/libs/binder/RpcSession.cpp
+++ b/libs/binder/RpcSession.cpp
@@ -20,6 +20,7 @@
 
 #include <dlfcn.h>
 #include <inttypes.h>
+#include <netinet/tcp.h>
 #include <poll.h>
 #include <unistd.h>
 
@@ -608,6 +609,18 @@
             return -savedErrno;
         }
 
+        if (addr.addr()->sa_family == AF_INET || addr.addr()->sa_family == AF_INET6) {
+            int noDelay = 1;
+            int result =
+                    setsockopt(serverFd.get(), IPPROTO_TCP, TCP_NODELAY, &noDelay, sizeof(noDelay));
+            if (result < 0) {
+                int savedErrno = errno;
+                ALOGE("Could not set TCP_NODELAY on %s: %s", addr.toString().c_str(),
+                      strerror(savedErrno));
+                return -savedErrno;
+            }
+        }
+
         RpcTransportFd transportFd(std::move(serverFd));
 
         if (0 != TEMP_FAILURE_RETRY(connect(transportFd.fd.get(), addr.addr(), addr.addrSize()))) {