Re: [PATCH v2 1/2]: perf util: map data buffer for preserving collected data

The data buffer and accompanying AIO control block are allocated at 
perf_mmap object and the mapped data buffer size is equal to 
the kernel one.

The buffer is then used to preserve profiling data ready for dumping 
and queue it for asynchronous writing into perf trace thru implemented 
record__aio_write() function.

mmap_aio control structure of the size equal to the number of per-cpu 
kernel buffers is used to keep pointers to enqueued AIO control 
blocks for monitoring of completed AIO operations.

Signed-off-by: Alexey Budankov <redacted>
---
Changes in v2:
- converted zalloc() to calloc() for allocation of mmap_aio array,
- cleared typo and adjusted fallback branch code;
---
tools/perf/builtin-record.c | 18 ++++++++++++++++++
 tools/perf/util/evlist.c    |  7 +++++++
 tools/perf/util/evlist.h    |  2 ++
 tools/perf/util/mmap.c      | 12 ++++++++++++
 tools/perf/util/mmap.h      |  3 +++
 5 files changed, 42 insertions(+)

diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
index 22ebeb92ac51..a35675e9f3aa 100644
--- a/tools/perf/builtin-record.c
+++ b/tools/perf/builtin-record.c

@@ -53,6 +53,7 @@
 #include <sys/mman.h>
 #include <sys/wait.h>
 #include <linux/time64.h>
+#include <aio.h>
 
 struct switch_output {
 	bool		 enabled;

@@ -121,6 +122,23 @@ static int record__write(struct record *rec, void *bf, size_t size)
 	return 0;
 }
 
+static int record__aio_write(int trace_fd, struct aiocb *cblock,
+		void *buf, size_t size, off_t off)
+{