From d98f4e8af5076e6a9dbd4ddc2c375cb7bcda8cd8 Mon Sep 17 00:00:00 2001
From: Riley Andrews <riandrews@google.com>
Date: Mon, 8 Jun 2015 23:36:34 -0700
Subject: [PATCH] Lower the priority of the threads in logd/logcat.

sched_batch implies only a penalty to latency in scheduling, but
does not imply that the process will be given less cpu time. Increase
the nice level to 10 to prioritize it below ui threads.

Bug: 21696721
Change-Id: I075af059dc755402f7df9b0d7a66cca921ff04b2
---
 logcat/logcat.cpp | 6 ++++++
 logd/main.cpp     | 7 +++++++
 2 files changed, 13 insertions(+)

diff --git a/logcat/logcat.cpp b/logcat/logcat.cpp
index 736e02eaa..e598bb810 100644
--- a/logcat/logcat.cpp
+++ b/logcat/logcat.cpp
@@ -14,6 +14,7 @@
 #include <stdlib.h>
 #include <string.h>
 #include <sys/cdefs.h>
+#include <sys/resource.h>
 #include <sys/socket.h>
 #include <sys/stat.h>
 #include <sys/types.h>
@@ -33,6 +34,7 @@
 #include <log/logd.h>
 #include <log/logger.h>
 #include <log/logprint.h>
+#include <utils/threads.h>
 
 #define DEFAULT_MAX_ROTATED_LOGS 4
 
@@ -221,6 +223,10 @@ static void setupOutput()
             fprintf(stderr, "failed to set to batch scheduler\n");
         }
 
+        if (setpriority(PRIO_PROCESS, 0, ANDROID_PRIORITY_BACKGROUND) < 0) {
+            fprintf(stderr, "failed set to priority\n");
+        }
+
         g_outFD = openLogFile (g_outputFileName);
 
         if (g_outFD < 0) {
diff --git a/logd/main.cpp b/logd/main.cpp
index 6db819e31..47f11fb89 100644
--- a/logd/main.cpp
+++ b/logd/main.cpp
@@ -27,6 +27,7 @@
 #include <sys/capability.h>
 #include <sys/klog.h>
 #include <sys/prctl.h>
+#include <sys/resource.h>
 #include <sys/stat.h>
 #include <sys/types.h>
 #include <syslog.h>
@@ -37,6 +38,7 @@
 #include <cutils/sockets.h>
 #include <log/event_tag_map.h>
 #include <private/android_filesystem_config.h>
+#include <utils/threads.h>
 
 #include "CommandListener.h"
 #include "LogBuffer.h"
@@ -91,6 +93,10 @@ static int drop_privs() {
         return -1;
     }
 
+    if (setpriority(PRIO_PROCESS, 0, ANDROID_PRIORITY_BACKGROUND) < 0) {
+        return -1;
+    }
+
     if (prctl(PR_SET_KEEPCAPS, 1) < 0) {
         return -1;
     }
@@ -156,6 +162,7 @@ static LogBuffer *logBuf = NULL;
 static void *reinit_thread_start(void * /*obj*/) {
     prctl(PR_SET_NAME, "logd.daemon");
     set_sched_policy(0, SP_BACKGROUND);
+    setpriority(PRIO_PROCESS, 0, ANDROID_PRIORITY_BACKGROUND);
 
     setgid(AID_SYSTEM);
     setuid(AID_SYSTEM);