[PATCH v12 1/3] perf util: map data buffer for preserving collected data

[Alexey Budankov]

The map->data buffer is used to preserve map->base profiling data 
for writing to disk. AIO map->cblock is used to queue corresponding 
map->data buffer for asynchronous writing.

Signed-off-by: Alexey Budankov <alexey.budankov@xxxxxxxxxxxxxxx>
---
Changes in v12:
 - applied stub functions design for the whole patch kit
 - grouped AIO related data into a struct under struct perf_mmap
Changes in v10:
 - moved specific code to perf_mmap__aio_mmap(), perf_mmap__aio_munmap()
 - adjusted error reporting by using %m
Changes in v9:
  - implemented NO_AIO and HAVE_AIO_SUPPORT defines to cover cases of 
    libc implementations without Posix AIO API support
Changes in v7:
  - implemented handling record.aio setting from perfconfig file
 Changes in v6:
  - adjusted setting of priorities for cblocks;
 Changes in v5:
  - reshaped layout of data structures;
  - implemented --aio option;
 Changes in v4:
  - converted mmap()/munmap() to malloc()/free() for mmap->data buffer management 
 Changes in v2:
  - converted zalloc() to calloc() for allocation of mmap_aio array,
  - cleared typo and adjusted fallback branch code;
---
 tools/perf/Makefile.config |  5 +++++
 tools/perf/Makefile.perf   |  7 ++++++-
 tools/perf/util/evlist.c   |  2 +-
 tools/perf/util/mmap.c     | 51 +++++++++++++++++++++++++++++++++++++++++++++-
 tools/perf/util/mmap.h     | 11 +++++++++-
 5 files changed, 72 insertions(+), 4 deletions(-)

diff --git a/tools/perf/Makefile.config b/tools/perf/Makefile.config
index f6d1a03c7523..2e90f4ce9214 100644
--- a/tools/perf/Makefile.config
+++ b/tools/perf/Makefile.config
@@ -355,6 +355,11 @@ endif # NO_LIBELF
 
 ifeq ($(feature-glibc), 1)
   CFLAGS += -DHAVE_GLIBC_SUPPORT
+  ifndef NO_AIO
+    ifndef BIONIC
+        CFLAGS += -DHAVE_AIO_SUPPORT
+    endif
+  endif
 endif
 
 ifdef NO_DWARF
diff --git a/tools/perf/Makefile.perf b/tools/perf/Makefile.perf
index 92514fb3689f..7becc6a72cf2 100644
--- a/tools/perf/Makefile.perf
+++ b/tools/perf/Makefile.perf
@@ -97,8 +97,13 @@ include ../scripts/utilities.mak
 # Define LIBCLANGLLVM if you DO want builtin clang and llvm support.
 # When selected, pass LLVM_CONFIG=/path/to/llvm-config to `make' if
 # llvm-config is not in $PATH.
-
+#
 # Define NO_CORESIGHT if you do not want support for CoreSight trace decoding.
+#
+# Define NO_AIO if you do not want support of Posix AIO based trace
+# streaming for record mode. Currently Posix AIO trace streaming is
+# supported only when linking with glibc.
+#
 
 # As per kernel Makefile, avoid funny character set dependencies
 unexport LC_ALL
diff --git a/tools/perf/util/evlist.c b/tools/perf/util/evlist.c
index be440df29615..1a83bf2c069c 100644
--- a/tools/perf/util/evlist.c
+++ b/tools/perf/util/evlist.c
@@ -1028,7 +1028,7 @@ int perf_evlist__mmap_ex(struct perf_evlist *evlist, unsigned int pages,
 	 * Its value is decided by evsel's write_backward.
 	 * So &mp should not be passed through const pointer.
 	 */
-	struct mmap_params mp;
+	struct mmap_params mp = { .nr_cblocks = 0 };
 
 	if (!evlist->mmap)
 		evlist->mmap = perf_evlist__alloc_mmap(evlist, false);
diff --git a/tools/perf/util/mmap.c b/tools/perf/util/mmap.c
index cdb95b3a1213..2c997d931106 100644
--- a/tools/perf/util/mmap.c
+++ b/tools/perf/util/mmap.c
@@ -153,8 +153,21 @@ void __weak auxtrace_mmap_params__set_idx(struct auxtrace_mmap_params *mp __mayb
 {
 }
 
+#ifdef HAVE_AIO_SUPPORT
+static void perf_mmap__aio_munmap(struct perf_mmap *map)
+{
+	if (map->aio.data)
+		zfree(&map->aio.data);
+}
+#else
+static void perf_mmap__aio_munmap(struct perf_mmap *map __maybe_unused)
+{
+}
+#endif
+
 void perf_mmap__munmap(struct perf_mmap *map)
 {
+	perf_mmap__aio_munmap(map);
 	if (map->base != NULL) {
 		munmap(map->base, perf_mmap__mmap_len(map));
 		map->base = NULL;
@@ -164,6 +177,42 @@ void perf_mmap__munmap(struct perf_mmap *map)
 	auxtrace_mmap__munmap(&map->auxtrace_mmap);
 }
 
+#ifdef HAVE_AIO_SUPPORT
+static int perf_mmap__aio_mmap(struct perf_mmap *map, struct mmap_params *mp)
+{
+	int delta_max;
+
+	if (mp->nr_cblocks) {
+		map->aio.data = malloc(perf_mmap__mmap_len(map));
+		if (!map->aio.data) {
+			pr_debug2("failed to allocate data buffer, error %m\n");
+			return -1;
+		}
+		/*
+		 * Use cblock.aio_fildes value different from -1
+		 * to denote started aio write operation on the
+		 * cblock so it requires explicit record__aio_sync()
+		 * call prior the cblock may be reused again.
+		 */
+		map->aio.cblock.aio_fildes = -1;
+		/*
+		 * Allocate cblock with max priority delta to
+		 * have faster aio write system calls.
+		 */
+		delta_max = sysconf(_SC_AIO_PRIO_DELTA_MAX);
+		map->aio.cblock.aio_reqprio = delta_max;
+	}
+
+	return 0;
+}
+#else
+static int perf_mmap__aio_mmap(struct perf_mmap *map __maybe_unused,
+			       struct mmap_params *mp __maybe_unused)
+{
+	return 0;
+}
+#endif
+
 int perf_mmap__mmap(struct perf_mmap *map, struct mmap_params *mp, int fd, int cpu)
 {
 	/*
@@ -197,7 +246,7 @@ int perf_mmap__mmap(struct perf_mmap *map, struct mmap_params *mp, int fd, int c
 				&mp->auxtrace_mp, map->base, fd))
 		return -1;
 
-	return 0;
+	return perf_mmap__aio_mmap(map, mp);
 }
 
 static int overwrite_rb_find_range(void *buf, int mask, u64 *start, u64 *end)
diff --git a/tools/perf/util/mmap.h b/tools/perf/util/mmap.h
index e603314dc792..a46dbdcdcc8a 100644
--- a/tools/perf/util/mmap.h
+++ b/tools/perf/util/mmap.h
@@ -6,6 +6,9 @@
 #include <linux/types.h>
 #include <asm/barrier.h>
 #include <stdbool.h>
+#ifdef HAVE_AIO_SUPPORT
+#include <aio.h>
+#endif
 #include "auxtrace.h"
 #include "event.h"
 
@@ -26,6 +29,12 @@ struct perf_mmap {
 	bool		 overwrite;
 	struct auxtrace_mmap auxtrace_mmap;
 	char		 event_copy[PERF_SAMPLE_MAX_SIZE] __aligned(8);
+#ifdef HAVE_AIO_SUPPORT
+	struct {
+		void 		 *data;
+		struct aiocb	 cblock;
+	} aio;
+#endif
 };
 
 /*
@@ -57,7 +66,7 @@ enum bkw_mmap_state {
 };
 
 struct mmap_params {
-	int			    prot, mask;
+	int			    prot, mask, nr_cblocks;
 	struct auxtrace_mmap_params auxtrace_mp;
 };