diff --git a/liblog/log_is_loggable.c b/liblog/log_is_loggable.c
index b4711d2..c73afcf 100644
--- a/liblog/log_is_loggable.c
+++ b/liblog/log_is_loggable.c
@@ -25,13 +25,18 @@
 
 static pthread_mutex_t lock_loggable = PTHREAD_MUTEX_INITIALIZER;
 
-static void lock()
+static int lock()
 {
     /*
      * If we trigger a signal handler in the middle of locked activity and the
      * signal handler logs a message, we could get into a deadlock state.
      */
-    pthread_mutex_lock(&lock_loggable);
+    /*
+     *  Any contention, and we can turn around and use the non-cached method
+     * in less time than the system call associated with a mutex to deal with
+     * the contention.
+     */
+    return pthread_mutex_trylock(&lock_loggable);
 }
 
 static void unlock()
@@ -45,6 +50,12 @@
     unsigned char c;
 };
 
+static int check_cache(struct cache *cache)
+{
+    return cache->pinfo
+        && __system_property_serial(cache->pinfo) != cache->serial;
+}
+
 #define BOOLEAN_TRUE 0xFF
 #define BOOLEAN_FALSE 0xFE
 
@@ -58,6 +69,7 @@
         if (!cache->pinfo) {
             return;
         }
+        cache->serial = -1;
     }
     serial = __system_property_serial(cache->pinfo);
     if (serial == cache->serial) {
@@ -85,7 +97,7 @@
     /* calculate the size of our key temporary buffer */
     const size_t taglen = (tag && *tag) ? strlen(tag) : 0;
     /* sizeof(log_namespace) = strlen(log_namespace) + 1 */
-    char key[sizeof(log_namespace) + taglen];
+    char key[sizeof(log_namespace) + taglen]; /* may be > PROPERTY_KEY_MAX */
     char *kp;
     size_t i;
     char c = 0;
@@ -101,48 +113,75 @@
     static char *last_tag;
     static uint32_t global_serial;
     uint32_t current_global_serial;
-    static struct cache tag_cache[2] = {
-        { NULL, -1, 0 },
-        { NULL, -1, 0 }
-    };
-    static struct cache global_cache[2] = {
-        { NULL, -1, 0 },
-        { NULL, -1, 0 }
-    };
+    static struct cache tag_cache[2];
+    static struct cache global_cache[2];
+    int change_detected;
+    int global_change_detected;
+    int not_locked;
 
     strcpy(key, log_namespace);
 
-    lock();
+    global_change_detected = change_detected = not_locked = lock();
 
-    current_global_serial = __system_property_area_serial();
+    if (!not_locked) {
+        /*
+         *  check all known serial numbers to changes.
+         */
+        for (i = 0; i < (sizeof(tag_cache) / sizeof(tag_cache[0])); ++i) {
+            if (check_cache(&tag_cache[i])) {
+                change_detected = 1;
+            }
+        }
+        for (i = 0; i < (sizeof(global_cache) / sizeof(global_cache[0])); ++i) {
+            if (check_cache(&global_cache[i])) {
+                global_change_detected = 1;
+            }
+        }
+
+        current_global_serial = __system_property_area_serial();
+        if (current_global_serial != global_serial) {
+            change_detected = 1;
+            global_change_detected = 1;
+        }
+    }
 
     if (taglen) {
-        uint32_t current_local_serial = current_global_serial;
-
-        if (!last_tag || (last_tag[0] != tag[0]) || strcmp(last_tag + 1, tag + 1)) {
-            /* invalidate log.tag.<tag> cache */
-            for(i = 0; i < (sizeof(tag_cache) / sizeof(tag_cache[0])); ++i) {
-                tag_cache[i].pinfo = NULL;
-                tag_cache[i].serial = -1;
-                tag_cache[i].c = '\0';
+        int local_change_detected = change_detected;
+        if (!not_locked) {
+            if (!last_tag
+                    || (last_tag[0] != tag[0])
+                    || strcmp(last_tag + 1, tag + 1)) {
+                /* invalidate log.tag.<tag> cache */
+                for (i = 0; i < (sizeof(tag_cache) / sizeof(tag_cache[0])); ++i) {
+                    tag_cache[i].pinfo = NULL;
+                    tag_cache[i].c = '\0';
+                }
+                free(last_tag);
+                last_tag = NULL;
+                local_change_detected = 1;
             }
-            free(last_tag);
-            last_tag = NULL;
-            current_global_serial = -1;
-        }
-        if (!last_tag) {
-            last_tag = strdup(tag);
+            if (!last_tag) {
+                last_tag = strdup(tag);
+            }
         }
         strcpy(key + sizeof(log_namespace) - 1, tag);
 
         kp = key;
-        for(i = 0; i < (sizeof(tag_cache) / sizeof(tag_cache[0])); ++i) {
-            if (current_local_serial != global_serial) {
-                refresh_cache(&tag_cache[i], kp);
+        for (i = 0; i < (sizeof(tag_cache) / sizeof(tag_cache[0])); ++i) {
+            struct cache *cache = &tag_cache[i];
+            struct cache temp_cache;
+
+            if (not_locked) {
+                temp_cache.pinfo = NULL;
+                temp_cache.c = '\0';
+                cache = &temp_cache;
+            }
+            if (local_change_detected) {
+                refresh_cache(cache, kp);
             }
 
-            if (tag_cache[i].c) {
-                c = tag_cache[i].c;
+            if (cache->c) {
+                c = cache->c;
                 break;
             }
 
@@ -166,13 +205,24 @@
         key[sizeof(log_namespace) - 2] = '\0';
 
         kp = key;
-        for(i = 0; i < (sizeof(global_cache) / sizeof(global_cache[0])); ++i) {
-            if (current_global_serial != global_serial) {
-                refresh_cache(&global_cache[i], kp);
+        for (i = 0; i < (sizeof(global_cache) / sizeof(global_cache[0])); ++i) {
+            struct cache *cache = &global_cache[i];
+            struct cache temp_cache;
+
+            if (not_locked) {
+                temp_cache = *cache;
+                if (temp_cache.pinfo != cache->pinfo) { /* check atomic */
+                    temp_cache.pinfo = NULL;
+                    temp_cache.c = '\0';
+                }
+                cache = &temp_cache;
+            }
+            if (global_change_detected) {
+                refresh_cache(cache, kp);
             }
 
-            if (global_cache[i].c) {
-                c = global_cache[i].c;
+            if (cache->c) {
+                c = cache->c;
                 break;
             }
 
@@ -181,9 +231,10 @@
         break;
     }
 
-    global_serial = current_global_serial;
-
-    unlock();
+    if (!not_locked) {
+        global_serial = current_global_serial;
+        unlock();
+    }
 
     switch (toupper(c)) {
     case 'V': return ANDROID_LOG_VERBOSE;
@@ -206,70 +257,103 @@
 }
 
 /*
- * Timestamp state generally remains constant, since a change is
- * rare, we can accept a trylock failure gracefully. Use a separate
- * lock from is_loggable to keep contention down b/25563384.
+ * For properties that are read often, but generally remain constant.
+ * Since a change is rare, we will accept a trylock failure gracefully.
+ * Use a separate lock from is_loggable to keep contention down b/25563384.
  */
-static pthread_mutex_t lock_clockid = PTHREAD_MUTEX_INITIALIZER;
+struct cache2 {
+    pthread_mutex_t lock;
+    uint32_t serial;
+    const char *key_persist;
+    struct cache cache_persist;
+    const char *key_ro;
+    struct cache cache_ro;
+    unsigned char (*const evaluate)(const struct cache2 *self);
+};
 
-clockid_t android_log_clockid()
+static inline unsigned char do_cache2(struct cache2 *self)
 {
-    static struct cache r_time_cache = { NULL, -1, 0 };
-    static struct cache p_time_cache = { NULL, -1, 0 };
-    char c;
+    uint32_t current_serial;
+    int change_detected;
+    unsigned char c;
 
-    if (pthread_mutex_trylock(&lock_clockid)) {
+    if (pthread_mutex_trylock(&self->lock)) {
         /* We are willing to accept some race in this context */
-        if (!(c = p_time_cache.c)) {
-            c = r_time_cache.c;
-        }
-    } else {
-        static uint32_t serial;
-        uint32_t current_serial = __system_property_area_serial();
-        if (current_serial != serial) {
-            refresh_cache(&r_time_cache, "ro.logd.timestamp");
-            refresh_cache(&p_time_cache, "persist.logd.timestamp");
-            serial = current_serial;
-        }
-        if (!(c = p_time_cache.c)) {
-            c = r_time_cache.c;
-        }
-
-        pthread_mutex_unlock(&lock_clockid);
+        return self->evaluate(self);
     }
 
-    return (tolower(c) == 'm') ? CLOCK_MONOTONIC : CLOCK_REALTIME;
+    change_detected = check_cache(&self->cache_persist)
+                   || check_cache(&self->cache_ro);
+    current_serial = __system_property_area_serial();
+    if (current_serial != self->serial) {
+        change_detected = 1;
+    }
+    if (change_detected) {
+        refresh_cache(&self->cache_persist, self->key_persist);
+        refresh_cache(&self->cache_ro, self->key_ro);
+        self->serial = current_serial;
+    }
+    c = self->evaluate(self);
+
+    pthread_mutex_unlock(&self->lock);
+
+    return c;
+}
+
+static unsigned char evaluate_persist_ro(const struct cache2 *self)
+{
+    unsigned char c = self->cache_persist.c;
+
+    if (c) {
+        return c;
+    }
+
+    return self->cache_ro.c;
 }
 
 /*
- * security state generally remains constant, since a change is
- * rare, we can accept a trylock failure gracefully.
+ * Timestamp state generally remains constant, but can change at any time
+ * to handle developer requirements.
  */
-static pthread_mutex_t lock_security = PTHREAD_MUTEX_INITIALIZER;
+clockid_t android_log_clockid()
+{
+    static struct cache2 clockid = {
+        PTHREAD_MUTEX_INITIALIZER,
+        0,
+        "persist.logd.timestamp",
+        { NULL, -1, '\0' },
+        "ro.logd.timestamp",
+        { NULL, -1, '\0' },
+        evaluate_persist_ro
+    };
+
+    return (tolower(do_cache2(&clockid)) == 'm')
+        ? CLOCK_MONOTONIC
+        : CLOCK_REALTIME;
+}
+
+/*
+ * Security state generally remains constant, but the DO must be able
+ * to turn off logging should it become spammy after an attack is detected.
+ */
+static unsigned char evaluate_security(const struct cache2 *self)
+{
+    unsigned char c = self->cache_ro.c;
+
+    return (c != BOOLEAN_FALSE) && c && (self->cache_persist.c == BOOLEAN_TRUE);
+}
 
 int __android_log_security()
 {
-    static struct cache r_do_cache = { NULL, -1, BOOLEAN_FALSE };
-    static struct cache p_security_cache = { NULL, -1, BOOLEAN_FALSE };
-    int retval;
+    static struct cache2 security = {
+        PTHREAD_MUTEX_INITIALIZER,
+        0,
+        "persist.logd.security",
+        { NULL, -1, BOOLEAN_FALSE },
+        "ro.device_owner",
+        { NULL, -1, BOOLEAN_FALSE },
+        evaluate_security
+    };
 
-    if (pthread_mutex_trylock(&lock_security)) {
-        /* We are willing to accept some race in this context */
-        retval = (r_do_cache.c != BOOLEAN_FALSE) && r_do_cache.c &&
-                 (p_security_cache.c == BOOLEAN_TRUE);
-    } else {
-        static uint32_t serial;
-        uint32_t current_serial = __system_property_area_serial();
-        if (current_serial != serial) {
-            refresh_cache(&r_do_cache, "ro.device_owner");
-            refresh_cache(&p_security_cache, "persist.logd.security");
-            serial = current_serial;
-        }
-        retval = (r_do_cache.c != BOOLEAN_FALSE) && r_do_cache.c &&
-                 (p_security_cache.c == BOOLEAN_TRUE);
-
-        pthread_mutex_unlock(&lock_security);
-    }
-
-    return retval;
+    return do_cache2(&security);
 }
diff --git a/liblog/tests/liblog_benchmark.cpp b/liblog/tests/liblog_benchmark.cpp
index 9f29a09..01fb50f 100644
--- a/liblog/tests/liblog_benchmark.cpp
+++ b/liblog/tests/liblog_benchmark.cpp
@@ -660,3 +660,31 @@
     StopBenchmarkTiming();
 }
 BENCHMARK(BM_is_loggable);
+
+/*
+ *	Measure the time it takes for android_log_clockid.
+ */
+static void BM_clockid(int iters) {
+    StartBenchmarkTiming();
+
+    for (int i = 0; i < iters; ++i) {
+        android_log_clockid();
+    }
+
+    StopBenchmarkTiming();
+}
+BENCHMARK(BM_clockid);
+
+/*
+ *	Measure the time it takes for __android_log_security.
+ */
+static void BM_security(int iters) {
+    StartBenchmarkTiming();
+
+    for (int i = 0; i < iters; ++i) {
+        __android_log_security();
+    }
+
+    StopBenchmarkTiming();
+}
+BENCHMARK(BM_security);