From: Sage Weil <sage@inktank.com>
Date: Fri, 27 Sep 2013 22:29:06 +0000 (-0700)
Subject: common/buffer: instrument utilization of cached crcs
X-Git-Tag: v0.72-rc1~42^2~10
X-Git-Url: http://git-server-git.apps.pok.os.sepia.ceph.com/?a=commitdiff_plain;h=6464516d9c852a1079f8bfc6d96a69b7c6c94aaa;p=ceph.git

common/buffer: instrument utilization of cached crcs

This is similar to the alloc tracking, but I've added a method to let
you enable it easily (in this case, from the unit test).

Signed-off-by: Sage Weil <sage@inktank.com>
---

diff --git a/src/common/buffer.cc b/src/common/buffer.cc
index 09dac01db175..3a8190f0280b 100644
--- a/src/common/buffer.cc
+++ b/src/common/buffer.cc
@@ -43,8 +43,8 @@ static uint32_t simple_spinlock_t buffer_debug_lock = SIMPLE_SPINLOCK_INITIALIZE
 # define bendl std::endl; }
 #endif
 
-atomic_t buffer_total_alloc;
-bool buffer_track_alloc = get_env_bool("CEPH_BUFFER_TRACK");
+  atomic_t buffer_total_alloc;
+  bool buffer_track_alloc = get_env_bool("CEPH_BUFFER_TRACK");
 
   void buffer::inc_total_alloc(unsigned len) {
     if (buffer_track_alloc)
@@ -58,6 +58,21 @@ bool buffer_track_alloc = get_env_bool("CEPH_BUFFER_TRACK");
     return buffer_total_alloc.read();
   }
 
+  atomic_t buffer_cached_crc;
+  atomic_t buffer_cached_crc_adjusted;
+  bool buffer_track_crc = get_env_bool("CEPH_BUFFER_TRACK");
+
+  void buffer::track_cached_crc(bool b) {
+    buffer_track_crc = b;
+  }
+  int buffer::get_cached_crc() {
+    return buffer_cached_crc.read();
+  }
+  int buffer::get_cached_crc_adjusted() {
+    return buffer_cached_crc_adjusted.read();
+  }
+
+
   class buffer::raw {
   public:
     char *data;
@@ -1311,6 +1326,8 @@ __u32 buffer::list::crc32c(__u32 crc) const
 	if (ccrc.first == crc) {
 	  // got it already
 	  crc = ccrc.second;
+	  if (buffer_track_crc)
+	    buffer_cached_crc.inc();
 	} else {
 	  /* If we have cached crc32c(buf, v) for initial value v,
 	   * we can convert this to a different initial value v' by:
@@ -1328,6 +1345,8 @@ __u32 buffer::list::crc32c(__u32 crc) const
 	  if (remaining)
 	    adjustment = ceph_crc32c(adjustment, zbuf, remaining);
 	  crc = ccrc.second ^ adjustment;
+	  if (buffer_track_crc)
+	    buffer_cached_crc_adjusted.inc();
 	}
       } else {
 	uint32_t base = crc;
diff --git a/src/include/buffer.h b/src/include/buffer.h
index ffa3d6e1b977..0b497a7cf38d 100644
--- a/src/include/buffer.h
+++ b/src/include/buffer.h
@@ -103,8 +103,20 @@ public:
   };
 
 
+  /// total bytes allocated
   static int get_total_alloc();
 
+  /// enable/disable alloc tracking
+  static void track_alloc(bool b);
+
+  /// count of cached crc hits (matching input)
+  static int get_cached_crc();
+  /// count of cached crc hits (mismatching input, required adjustment)
+  static int get_cached_crc_adjusted();
+  /// enable/disable tracking of cached crcs
+  static void track_cached_crc(bool b);
+
+
 private:
  
   /* hack for memory utilization debugging. */