bufmon: add buffer monitoring plugin

This plugin allow to keep track of buffer usage in VPP graph nodes. The
main use is to detect buffer leakages.

Type: feature

Change-Id: Iadcf4ab98207fab6e2fa375060879bc2a25b711e
Signed-off-by: Benoît Ganne <bganne@cisco.com>

7 files changed, 417 insertions, 24 deletions

diff --git a/src/plugins/bufmon/CMakeLists.txt b/src/plugins/bufmon/CMakeLists.txt
new file mode 100644
index 00000000000..bf929598f92
--- /dev/null
+++ b/src/plugins/bufmon/CMakeLists.txt
@@ -0,0 +1,17 @@
+# Copyright (c) 2020 Cisco and/or its affiliates.
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at:
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+add_vpp_plugin(bufmon
+  SOURCES
+  bufmon.c
+)
diff --git a/src/plugins/bufmon/FEATURE.yaml b/src/plugins/bufmon/FEATURE.yaml
new file mode 100644
index 00000000000..639643e5a28
--- /dev/null
+++ b/src/plugins/bufmon/FEATURE.yaml
@@ -0,0 +1,8 @@
+---
+name: Buffers monitoring plugin
+maintainer: Benoît Ganne <bganne@cisco.com>
+features:
+  - monitor buffer utiization in VPP graph nodes
+description: "monitor buffer utiization in VPP graph nodes"
+state: production
+properties: [CLI, MULTITHREAD]
diff --git a/src/plugins/bufmon/bufmon.c b/src/plugins/bufmon/bufmon.c
new file mode 100644
index 00000000000..2a35acce482
--- /dev/null
+++ b/src/plugins/bufmon/bufmon.c
@@ -0,0 +1,313 @@
+#include <vlib/vlib.h>
+#include <vnet/plugin/plugin.h>
+#include <vpp/app/version.h>
+
+typedef struct
+{
+  u64 in;
+  u64 out;
+  u64 alloc;
+  u64 free;
+} bufmon_per_node_data_t;
+
+typedef struct
+{
+  CLIB_CACHE_LINE_ALIGN_MARK (cacheline0);
+  bufmon_per_node_data_t *pnd;
+  u32 cur_node;
+} bufmon_per_thread_data_t;
+
+typedef struct
+{
+  bufmon_per_thread_data_t *ptd;
+  int enabled;
+} bufmon_main_t;
+
+static bufmon_main_t bufmon_main;
+
+static u32
+bufmon_alloc_free_callback (vlib_main_t *vm, u32 n_buffers, const int is_free)
+{
+  bufmon_main_t *bm = &bufmon_main;
+  bufmon_per_thread_data_t *ptd;
+  bufmon_per_node_data_t *pnd;
+  u32 cur_node;
+
+  if (PREDICT_FALSE (vm->thread_index >= vec_len (bm->ptd)))
+    {
+      clib_warning ("bufmon: thread index %d unknown for buffer %s (%d)",
+		    vm->thread_index, is_free ? "free" : "alloc", n_buffers);
+      return n_buffers;
+    }
+
+  ptd = vec_elt_at_index (bm->ptd, vm->thread_index);
+
+  cur_node = ptd->cur_node;
+  if (cur_node >= vec_len (ptd->pnd))
+    {
+      cur_node = vlib_get_current_process_node_index (vm);
+      vec_validate_aligned (ptd->pnd, cur_node, CLIB_CACHE_LINE_BYTES);
+    }
+
+  pnd = vec_elt_at_index (ptd->pnd, cur_node);
+
+  if (is_free)
+    pnd->free += n_buffers;
+  else
+    pnd->alloc += n_buffers;
+
+  return n_buffers;
+}
+
+static u32
+bufmon_alloc_callback (vlib_main_t *vm, u8 buffer_pool_index, u32 *buffers,
+		       u32 n_buffers)
+{
+  return bufmon_alloc_free_callback (vm, n_buffers, 0 /* is_free */);
+}
+
+static u32
+bufmon_free_callback (vlib_main_t *vm, u8 buffer_pool_index, u32 *buffers,
+		      u32 n_buffers)
+{
+  return bufmon_alloc_free_callback (vm, n_buffers, 1 /* is_free */);
+}
+
+static u32
+bufmon_count_buffers (vlib_main_t *vm, vlib_frame_t *frame)
+{
+  vlib_buffer_t *b[VLIB_FRAME_SIZE];
+  u32 *from = vlib_frame_vector_args (frame);
+  const u32 n = frame->n_vectors;
+  u32 nc = 0;
+  u32 i;
+
+  vlib_get_buffers (vm, from, b, n);
+
+  for (i = 0; i < n; i++)
+    {
+      const vlib_buffer_t *cb = b[i];
+      while (cb->flags & VLIB_BUFFER_NEXT_PRESENT)
+	{
+	  nc++;
+	  cb = vlib_get_buffer (vm, cb->next_buffer);
+	}
+    }
+
+  return n + nc;
+}
+
+static uword
+bufmon_dispatch_wrapper (vlib_main_t *vm, vlib_node_runtime_t *node,
+			 vlib_frame_t *frame)
+{
+  vlib_node_main_t *nm = &vm->node_main;
+  bufmon_main_t *bm = &bufmon_main;
+  bufmon_per_thread_data_t *ptd;
+  bufmon_per_node_data_t *pnd;
+  int pending_frames;
+  uword rv;
+
+  vec_validate_aligned (bm->ptd, vm->thread_index, CLIB_CACHE_LINE_BYTES);
+  ptd = vec_elt_at_index (bm->ptd, vm->thread_index);
+  vec_validate_aligned (ptd->pnd, node->node_index, CLIB_CACHE_LINE_BYTES);
+  pnd = vec_elt_at_index (ptd->pnd, node->node_index);
+
+  if (frame)
+    pnd->in += bufmon_count_buffers (vm, frame);
+
+  pending_frames = vec_len (nm->pending_frames);
+  ptd->cur_node = node->node_index;
+
+  rv = node->function (vm, node, frame);
+
+  ptd->cur_node = ~0;
+  for (; pending_frames < vec_len (nm->pending_frames); pending_frames++)
+    {
+      vlib_pending_frame_t *p =
+	vec_elt_at_index (nm->pending_frames, pending_frames);
+      pnd->out += bufmon_count_buffers (vm, vlib_get_frame (vm, p->frame));
+    }
+
+  return rv;
+}
+
+static void
+bufmon_unregister_callbacks (vlib_main_t *vm)
+{
+  vlib_buffer_set_alloc_free_callback (vm, 0, 0);
+  foreach_vlib_main ()
+    vlib_node_set_dispatch_wrapper (this_vlib_main, 0);
+}
+
+static clib_error_t *
+bufmon_register_callbacks (vlib_main_t *vm)
+{
+  if (vlib_buffer_set_alloc_free_callback (vm, bufmon_alloc_callback,
+					   bufmon_free_callback))
+    goto err0;
+
+  foreach_vlib_main ()
+    if (vlib_node_set_dispatch_wrapper (this_vlib_main,
+					bufmon_dispatch_wrapper))
+      goto err1;
+
+  return 0;
+
+err1:
+  foreach_vlib_main ()
+    vlib_node_set_dispatch_wrapper (this_vlib_main, 0);
+err0:
+  vlib_buffer_set_alloc_free_callback (vm, 0, 0);
+  return clib_error_return (0, "failed to register callback");
+}
+
+static clib_error_t *
+bufmon_enable_disable (vlib_main_t *vm, int enable)
+{
+  bufmon_main_t *bm = &bufmon_main;
+
+  if (enable)
+    {
+      if (bm->enabled)
+	return 0;
+      clib_error_t *error = bufmon_register_callbacks (vm);
+      if (error)
+	return error;
+      bm->enabled = 1;
+    }
+  else
+    {
+      if (!bm->enabled)
+	return 0;
+      bufmon_unregister_callbacks (vm);
+      bm->enabled = 0;
+    }
+
+  return 0;
+}
+
+static clib_error_t *
+set_buffer_traces (vlib_main_t *vm, unformat_input_t *input,
+		   vlib_cli_command_t *cmd)
+{
+  unformat_input_t _line_input, *line_input = &_line_input;
+  int on = 1;
+
+  if (unformat_user (input, unformat_line_input, line_input))
+    {
+      while (unformat_check_input (line_input) != UNFORMAT_END_OF_INPUT)
+	{
+	  if (unformat (line_input, "on"))
+	    on = 1;
+	  else if (unformat (line_input, "off"))
+	    on = 0;
+	  else
+	    {
+	      unformat_free (line_input);
+	      return clib_error_return (0, "unknown input `%U'",
+					format_unformat_error, line_input);
+	    }
+	}
+      unformat_free (line_input);
+    }
+
+  return bufmon_enable_disable (vm, on);
+}
+
+VLIB_CLI_COMMAND (set_buffer_traces_command, static) = {
+  .path = "set buffer traces",
+  .short_help = "set buffer traces [on|off]",
+  .function = set_buffer_traces,
+};
+
+static clib_error_t *
+show_buffer_traces (vlib_main_t *vm, unformat_input_t *input,
+		    vlib_cli_command_t *cmd)
+{
+  unformat_input_t _line_input, *line_input = &_line_input;
+  const bufmon_main_t *bm = &bufmon_main;
+  const bufmon_per_thread_data_t *ptd;
+  const bufmon_per_node_data_t *pnd;
+  int verbose = 0;
+  int status = 0;
+
+  if (unformat_user (input, unformat_line_input, line_input))
+    {
+      while (unformat_check_input (line_input) != UNFORMAT_END_OF_INPUT)
+	{
+	  if (unformat (line_input, "verbose"))
+	    verbose = 1;
+	  else if (unformat (line_input, "status"))
+	    status = 1;
+	  else
+	    {
+	      unformat_free (line_input);
+	      return clib_error_return (0, "unknown input `%U'",
+					format_unformat_error, line_input);
+	    }
+	}
+      unformat_free (line_input);
+    }
+
+  if (status)
+    {
+      vlib_cli_output (vm, "buffers tracing is %s",
+		       bm->enabled ? "on" : "off");
+      return 0;
+    }
+
+  vlib_cli_output (vm, "%U\n\n", format_vlib_buffer_pool_all, vm);
+  vlib_cli_output (vm, "%30s%20s%20s%20s%20s%20s", "Node", "Allocated",
+		   "Freed", "In", "Out", "Buffered");
+  vec_foreach (ptd, bm->ptd)
+    {
+      vec_foreach (pnd, ptd->pnd)
+	{
+	  const u64 in = pnd->alloc + pnd->in;
+	  const u64 out = pnd->free + pnd->out;
+	  const i64 buffered = in - out;
+	  if (0 == in && 0 == out)
+	    continue; /* skip nodes w/o activity */
+	  if (0 == buffered && !verbose)
+	    continue; /* if not verbose, skip nodes w/o buffered buffers */
+	  vlib_cli_output (vm, "%30U%20lu%20lu%20lu%20lu%20ld",
+			   format_vlib_node_name, vm, pnd - ptd->pnd,
+			   pnd->alloc, pnd->free, pnd->in, pnd->out, buffered);
+	}
+    }
+
+  return 0;
+}
+
+VLIB_CLI_COMMAND (show_buffer_traces_command, static) = {
+  .path = "show buffer traces",
+  .short_help = "show buffer traces [status|verbose]",
+  .function = show_buffer_traces,
+};
+
+static clib_error_t *
+clear_buffer_traces (vlib_main_t *vm, unformat_input_t *input,
+		     vlib_cli_command_t *cmd)
+{
+  const bufmon_main_t *bm = &bufmon_main;
+  const bufmon_per_thread_data_t *ptd;
+  const bufmon_per_node_data_t *pnd;
+
+  vec_foreach (ptd, bm->ptd)
+    vec_foreach (pnd, ptd->pnd)
+      vec_reset_length (pnd);
+
+  return 0;
+}
+
+VLIB_CLI_COMMAND (clear_buffers_trace_command, static) = {
+  .path = "clear buffer traces",
+  .short_help = "clear buffer traces",
+  .function = clear_buffer_traces,
+};
+
+VLIB_PLUGIN_REGISTER () = {
+  .version = VPP_BUILD_VER,
+  .description = "Buffers monitoring plugin",
+};
diff --git a/src/plugins/bufmon/bufmon_doc.md b/src/plugins/bufmon/bufmon_doc.md
new file mode 100644
index 00000000000..bfa88f40a7d
--- /dev/null
+++ b/src/plugins/bufmon/bufmon_doc.md
@@ -0,0 +1,24 @@
+# Buffers monitoring plugin {#bufmon_doc}
+
+This plugin enables to track buffer utilization in the VPP graph nodes. The
+main use is to detect buffer leakage.
+It works by keeping track of number of buffer allocations and free in graph
+nodes and also of number of buffers received in input frames and in output
+frames.
+The formula to compute the number of "buffered" buffers in a node is simply:
+        #buffered = #alloc + #input - #free - #output
+Note: monitoring will impact performances.
+
+## Basic usage
+1. Turn buffer traces on:
+```
+~# vppctl set buffer traces on
+```
+2. Monitor buffer usage:
+```
+~# vppctl show buffer traces verbose
+```
+3. Turn buffer traces off:
+```
+~# vppctl set buffer traces off
+```
diff --git a/src/vlib/buffer.c b/src/vlib/buffer.c
index adaafa36f5d..71f84d377af 100644
--- a/src/vlib/buffer.c
+++ b/src/vlib/buffer.c
@@ -615,20 +615,26 @@ format_vlib_buffer_pool (u8 * s, va_list * va)
   return s;
 }
 
-static clib_error_t *
-show_buffers (vlib_main_t * vm,
-	      unformat_input_t * input, vlib_cli_command_t * cmd)
+u8 *
+format_vlib_buffer_pool_all (u8 *s, va_list *va)
 {
+  vlib_main_t *vm = va_arg (*va, vlib_main_t *);
   vlib_buffer_main_t *bm = vm->buffer_main;
   vlib_buffer_pool_t *bp;
 
-  vlib_cli_output (vm, "%U", format_vlib_buffer_pool, vm, 0);
+  s = format (s, "%U", format_vlib_buffer_pool, vm, 0);
 
-  /* *INDENT-OFF* */
   vec_foreach (bp, bm->buffer_pools)
-    vlib_cli_output (vm, "%U", format_vlib_buffer_pool, vm, bp);
-  /* *INDENT-ON* */
+    s = format (s, "\n%U", format_vlib_buffer_pool, vm, bp);
+
+  return s;
+}
 
+static clib_error_t *
+show_buffers (vlib_main_t *vm, unformat_input_t *input,
+	      vlib_cli_command_t *cmd)
+{
+  vlib_cli_output (vm, "%U", format_vlib_buffer_pool_all, vm);
   return 0;
 }
 
@@ -971,6 +977,20 @@ vlib_buffer_alloc_may_fail (vlib_main_t * vm, u32 n_buffers)
 }
 #endif
 
+__clib_export int
+vlib_buffer_set_alloc_free_callback (
+  vlib_main_t *vm, vlib_buffer_alloc_free_callback_t *alloc_callback_fn,
+  vlib_buffer_alloc_free_callback_t *free_callback_fn)
+{
+  vlib_buffer_main_t *bm = vm->buffer_main;
+  if ((alloc_callback_fn && bm->alloc_callback_fn) ||
+      (free_callback_fn && bm->free_callback_fn))
+    return 1;
+  bm->alloc_callback_fn = alloc_callback_fn;
+  bm->free_callback_fn = free_callback_fn;
+  return 0;
+}
+
 /** @endcond */
 /*
  * fd.io coding-style-patch-verification: ON
diff --git a/src/vlib/buffer.h b/src/vlib/buffer.h
index 349b7324996..b548adf4be8 100644
--- a/src/vlib/buffer.h
+++ b/src/vlib/buffer.h
@@ -472,6 +472,10 @@ typedef struct
 
 #define VLIB_BUFFER_MAX_NUMA_NODES 32
 
+typedef u32 (vlib_buffer_alloc_free_callback_t) (struct vlib_main_t *vm,
+						 u8 buffer_pool_index,
+						 u32 *buffers, u32 n_buffers);
+
 typedef struct
 {
   CLIB_CACHE_LINE_ALIGN_MARK (cacheline0);
@@ -481,12 +485,9 @@ typedef struct
   uword buffer_mem_size;
   vlib_buffer_pool_t *buffer_pools;
 
-  /* Hash table mapping buffer index into number
-     0 => allocated but free, 1 => allocated and not-free.
-     If buffer index is not in hash table then this buffer
-     has never been allocated. */
-  uword *buffer_known_hash;
-  clib_spinlock_t buffer_known_hash_lockp;
+  vlib_buffer_alloc_free_callback_t *alloc_callback_fn;
+  vlib_buffer_alloc_free_callback_t *free_callback_fn;
+
   u8 default_buffer_pool_index_for_numa[VLIB_BUFFER_MAX_NUMA_NODES];
 
   /* config */
@@ -495,12 +496,25 @@ typedef struct
   u32 default_data_size;
   clib_mem_page_sz_t log2_page_size;
 
+  /* Hash table mapping buffer index into number
+     0 => allocated but free, 1 => allocated and not-free.
+     If buffer index is not in hash table then this buffer
+     has never been allocated. */
+  uword *buffer_known_hash;
+  clib_spinlock_t buffer_known_hash_lockp;
+
   /* logging */
   vlib_log_class_t log_default;
 } vlib_buffer_main_t;
 
 clib_error_t *vlib_buffer_main_init (struct vlib_main_t *vm);
 
+format_function_t format_vlib_buffer_pool_all;
+
+int vlib_buffer_set_alloc_free_callback (
+  struct vlib_main_t *vm, vlib_buffer_alloc_free_callback_t *alloc_callback_fn,
+  vlib_buffer_alloc_free_callback_t *free_callback_fn);
+
 extern u16 __vlib_buffer_external_hdr_size;
 #define VLIB_BUFFER_SET_EXT_HDR_SIZE(x) \
 static void __clib_constructor \
diff --git a/src/vlib/buffer_funcs.h b/src/vlib/buffer_funcs.h
index 89a765ee0d3..77964fde821 100644
--- a/src/vlib/buffer_funcs.h
+++ b/src/vlib/buffer_funcs.h
@@ -626,11 +626,7 @@ vlib_buffer_alloc_from_pool (vlib_main_t * vm, u32 * buffers, u32 n_buffers,
       src = bpt->cached_buffers + len - n_buffers;
       vlib_buffer_copy_indices (dst, src, n_buffers);
       bpt->n_cached -= n_buffers;
-
-      if (CLIB_DEBUG > 0)
-	vlib_buffer_validate_alloc_free (vm, buffers, n_buffers,
-					 VLIB_BUFFER_KNOWN_FREE);
-      return n_buffers;
+      goto done;
     }
 
   /* alloc bigger than cache - take buffers directly from main pool */
@@ -638,11 +634,7 @@ vlib_buffer_alloc_from_pool (vlib_main_t * vm, u32 * buffers, u32 n_buffers,
     {
       n_buffers = vlib_buffer_pool_get (vm, buffer_pool_index, buffers,
 					n_buffers);
-
-      if (CLIB_DEBUG > 0)
-	vlib_buffer_validate_alloc_free (vm, buffers, n_buffers,
-					 VLIB_BUFFER_KNOWN_FREE);
-      return n_buffers;
+      goto done;
     }
 
   /* take everything available in the cache */
@@ -670,11 +662,13 @@ vlib_buffer_alloc_from_pool (vlib_main_t * vm, u32 * buffers, u32 n_buffers,
 
   n_buffers -= n_left;
 
+done:
   /* Verify that buffers are known free. */
   if (CLIB_DEBUG > 0)
     vlib_buffer_validate_alloc_free (vm, buffers, n_buffers,
 				     VLIB_BUFFER_KNOWN_FREE);
-
+  if (PREDICT_FALSE (bm->alloc_callback_fn != 0))
+    bm->alloc_callback_fn (vm, buffer_pool_index, buffers, n_buffers);
   return n_buffers;
 }
 
@@ -776,6 +770,7 @@ static_always_inline void
 vlib_buffer_pool_put (vlib_main_t * vm, u8 buffer_pool_index,
 		      u32 * buffers, u32 n_buffers)
 {
+  vlib_buffer_main_t *bm = vm->buffer_main;
   vlib_buffer_pool_t *bp = vlib_get_buffer_pool (vm, buffer_pool_index);
   vlib_buffer_pool_thread_t *bpt = vec_elt_at_index (bp->threads,
 						     vm->thread_index);
@@ -784,6 +779,8 @@ vlib_buffer_pool_put (vlib_main_t * vm, u8 buffer_pool_index,
   if (CLIB_DEBUG > 0)
     vlib_buffer_validate_alloc_free (vm, buffers, n_buffers,
 				     VLIB_BUFFER_KNOWN_ALLOCATED);
+  if (PREDICT_FALSE (bm->free_callback_fn != 0))
+    bm->free_callback_fn (vm, buffer_pool_index, buffers, n_buffers);
 
   n_cached = bpt->n_cached;
   n_empty = VLIB_BUFFER_POOL_PER_THREAD_CACHE_SZ - n_cached;