From 3ef0876b95a6ff342bc348f5603ae282265f0ca1 Mon Sep 17 00:00:00 2001
From: antirez <antirez@gmail.com>
Date: Wed, 12 Nov 2014 10:43:32 +0100
Subject: [PATCH] THP detection / reporting functions added.

---
 src/latency.c | 26 ++++++++++++++++++++++++++
 src/zmalloc.c | 24 ++++++++++++++++++------
 src/zmalloc.h |  1 +
 3 files changed, 45 insertions(+), 6 deletions(-)

diff --git a/src/latency.c b/src/latency.c
index b7845ca2..2e239571 100644
--- a/src/latency.c
+++ b/src/latency.c
@@ -56,6 +56,32 @@ dictType latencyTimeSeriesDictType = {
     dictVanillaFree             /* val destructor */
 };
 
+/* ------------------------- Utility functions ------------------------------ */
+
+#ifdef __linux__
+/* Returns 1 if Transparent Huge Pages support is enabled in the kernel.
+ * Otherwise (or if we are unable to check) 0 is returned. */
+int THPIsEnabled(void) {
+    char buf[1024];
+
+    FILE *fp = fopen("/sys/kernel/mm/transparent_hugepage/enabled","r");
+    if (!fp) return 0;
+    if (fgets(buf,sizeof(buf),fp) == NULL) {
+        fclose(fp);
+        return 0;
+    }
+    fclose(fp);
+    return (strstr(buf,"[never]") == NULL) ? 1 : 0;
+}
+
+/* Report the amount of AnonHugePages in smap, in bytes. If the return
+ * value of the function is non-zero, the process is being targeted by
+ * THP support, and is likely to have memory usage / latency issues. */
+int THPGetAnonHugePagesSize(void) {
+    return zmalloc_get_smap_bytes_by_field("AnonHugePages:");
+}
+#endif
+
 /* ---------------------------- Latency API --------------------------------- */
 
 /* Latency monitor initialization. We just need to create the dictionary
diff --git a/src/zmalloc.c b/src/zmalloc.c
index 11616e5a..e5835372 100644
--- a/src/zmalloc.c
+++ b/src/zmalloc.c
@@ -328,27 +328,39 @@ float zmalloc_get_fragmentation_ratio(size_t rss) {
     return (float)rss/zmalloc_used_memory();
 }
 
+/* Get the sum of the specified field (converted form kb to bytes) in
+ * /proc/self/smaps. The field must be specified with trailing ":" as it
+ * apperas in the smaps output.
+ *
+ * Example: zmalloc_get_smap_bytes_by_field("Rss:");
+ */
 #if defined(HAVE_PROC_SMAPS)
-size_t zmalloc_get_private_dirty(void) {
+size_t zmalloc_get_smap_bytes_by_field(char *field) {
     char line[1024];
-    size_t pd = 0;
+    size_t bytes = 0;
     FILE *fp = fopen("/proc/self/smaps","r");
+    int flen = strlen(field);
 
     if (!fp) return 0;
     while(fgets(line,sizeof(line),fp) != NULL) {
-        if (strncmp(line,"Private_Dirty:",14) == 0) {
+        if (strncmp(line,field,flen) == 0) {
             char *p = strchr(line,'k');
             if (p) {
                 *p = '\0';
-                pd += strtol(line+14,NULL,10) * 1024;
+                bytes += strtol(line+flen,NULL,10) * 1024;
             }
         }
     }
     fclose(fp);
-    return pd;
+    return bytes;
 }
 #else
-size_t zmalloc_get_private_dirty(void) {
+size_t zmalloc_get_smap_bytes_by_field(char *field) {
+    REDIS_NOTUSED(field);
     return 0;
 }
 #endif
+
+size_t zmalloc_get_private_dirty(void) {
+    return zmalloc_get_smap_bytes_by_field("Private_Dirty:");
+}
diff --git a/src/zmalloc.h b/src/zmalloc.h
index 72a4f813..4de2cffe 100644
--- a/src/zmalloc.h
+++ b/src/zmalloc.h
@@ -76,6 +76,7 @@ void zmalloc_set_oom_handler(void (*oom_handler)(size_t));
 float zmalloc_get_fragmentation_ratio(size_t rss);
 size_t zmalloc_get_rss(void);
 size_t zmalloc_get_private_dirty(void);
+size_t zmalloc_get_smap_bytes_by_field(char *field);
 void zlibc_free(void *ptr);
 
 #ifndef HAVE_MALLOC_SIZE