perfmon: make less arch dependent

In preparation for enabling perfmon on Arm platforms, move some Intel
/arch specific logic into the /intel directory and update the CMake to
split the common code from arch specific files.

Since the dispatch_wrapper code is very different on Arm/Intel,
each arch can provide their own implementation + conduct any additional
arch specific config e.g. on Intel, all indexes from the mmap pages are
cached. The new method intel_config_dispatch_wrapper conducts this
config and returns a pointer to the dispatch wrapper to use.

Similarly, is_bundle_supported() looks very different on Arm/Intel, so
each implementation is to provide their own arch specific checks.

Two new callbacks/function ptrs are added in PERFMON_REGISTER_SOURCE to
support this - .bundle_support and .config_dispatch_wrapper.

Type: refactor
Signed-off-by: Zachary Leaf <zachary.leaf@arm.com>
Change-Id: Idd121ddcfd1cc80a57c949cecd64eb2db0ac8be3

1 files changed, 160 insertions, 0 deletions

diff --git a/src/plugins/perfmon/intel/dispatch_wrapper.c b/src/plugins/perfmon/intel/dispatch_wrapper.c
new file mode 100644
index 00000000000..d424b54b85f
--- /dev/null
+++ b/src/plugins/perfmon/intel/dispatch_wrapper.c
@@ -0,0 +1,160 @@
+/*
+ * 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.
+ */
+
+#include "vppinfra/string.h"
+#include <vnet/vnet.h>
+
+#include <vlibapi/api.h>
+#include <vlibmemory/api.h>
+#include <vnet/plugin/plugin.h>
+#include <vpp/app/version.h>
+#include <linux/limits.h>
+#include <sys/ioctl.h>
+
+#include <perfmon/perfmon.h>
+
+vlib_node_function_t *perfmon_dispatch_wrappers[PERF_MAX_EVENTS + 1];
+
+static_always_inline void
+perfmon_read_pmcs (u64 *counters, u32 *indexes, u8 n_counters)
+{
+  for (int i = 0; i < n_counters; i++)
+    counters[i] = _rdpmc (indexes[i] - 1);
+}
+
+static_always_inline uword
+perfmon_dispatch_wrapper_inline (vlib_main_t *vm, vlib_node_runtime_t *node,
+				 vlib_frame_t *frame, u8 n_events)
+{
+  perfmon_main_t *pm = &perfmon_main;
+  perfmon_thread_runtime_t *rt =
+    vec_elt_at_index (pm->thread_runtimes, vm->thread_index);
+  perfmon_node_stats_t *s =
+    vec_elt_at_index (rt->node_stats, node->node_index);
+
+  struct
+  {
+    u64 t[2][PERF_MAX_EVENTS];
+  } samples;
+  uword rv;
+
+  clib_prefetch_load (s);
+
+  perfmon_read_pmcs (&samples.t[0][0], &rt->indexes[0], n_events);
+  rv = node->function (vm, node, frame);
+  perfmon_read_pmcs (&samples.t[1][0], &rt->indexes[0], n_events);
+
+  if (rv == 0)
+    return rv;
+
+  s->n_calls += 1;
+  s->n_packets += rv;
+
+  for (int i = 0; i < n_events; i++)
+    {
+      if (!(rt->preserve_samples & 1 << i))
+	{
+	  s->value[i] += samples.t[1][i] - samples.t[0][i];
+	}
+      else
+	{
+	  s->t[0].value[i] = samples.t[0][i];
+	  s->t[1].value[i] = samples.t[1][i];
+	}
+    }
+
+  return rv;
+}
+
+static_always_inline u32
+perfmon_mmap_read_index (const struct perf_event_mmap_page *mmap_page)
+{
+  u32 idx;
+  u32 seq;
+
+  /* See documentation in /usr/include/linux/perf_event.h, for more details
+   * but the 2 main important things are:
+   *  1) if seq != mmap_page->lock, it means the kernel is currently updating
+   *     the user page and we need to read it again
+   *  2) if idx == 0, it means the perf event is currently turned off and we
+   *     just need to read the kernel-updated 'offset', otherwise we must also
+   *     add the current hw value (hence rdmpc) */
+  do
+    {
+      seq = mmap_page->lock;
+      CLIB_COMPILER_BARRIER ();
+
+      idx = mmap_page->index;
+
+      CLIB_COMPILER_BARRIER ();
+    }
+  while (mmap_page->lock != seq);
+
+  return idx;
+}
+
+static_always_inline clib_error_t *
+read_mmap_indexes (perfmon_bundle_t *b)
+{
+  perfmon_main_t *pm = &perfmon_main;
+  for (int i = 0; i < vec_len (pm->thread_runtimes); i++)
+    {
+      perfmon_thread_runtime_t *tr;
+      tr = vec_elt_at_index (pm->thread_runtimes, i);
+
+      for (int j = 0; j < b->n_events; j++)
+	{
+	  tr->indexes[j] = perfmon_mmap_read_index (tr->mmap_pages[j]);
+
+	  /* if a zero index is returned generate error */
+	  if (!tr->indexes[j])
+	    {
+	      return clib_error_return (0, "invalid rdpmc index");
+	    }
+	}
+    }
+  return 0;
+}
+
+clib_error_t *
+intel_config_dispatch_wrapper (perfmon_bundle_t *b,
+			       vlib_node_function_t **dispatch_wrapper)
+{
+  clib_error_t *err = 0;
+  if ((err = read_mmap_indexes (b)) != 0)
+    return err;
+
+  (*dispatch_wrapper) = perfmon_dispatch_wrappers[b->n_events];
+  return 0;
+}
+
+#define foreach_n_events                                                      \
+  _ (1) _ (2) _ (3) _ (4) _ (5) _ (6) _ (7) _ (8) _ (9) _ (10) _ (11) _ (12)
+
+#define _(x)                                                                  \
+  static uword perfmon_dispatch_wrapper##x (                                  \
+    vlib_main_t *vm, vlib_node_runtime_t *node, vlib_frame_t *frame)          \
+  {                                                                           \
+    return perfmon_dispatch_wrapper_inline (vm, node, frame, x);              \
+  }
+
+foreach_n_events
+#undef _
+
+  vlib_node_function_t *perfmon_dispatch_wrappers[PERF_MAX_EVENTS + 1] = {
+#define _(x) [x] = &perfmon_dispatch_wrapper##x,
+    foreach_n_events
+#undef _
+  };