[PATCH v8 1/3]: perf util: map data buffer for preserving collected data

From: Alexey Budankov
Date: Fri Sep 07 2018 - 03:11:10 EST



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 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/util/mmap.c | 25 +++++++++++++++++++++++++
tools/perf/util/mmap.h | 3 +++
2 files changed, 28 insertions(+)

diff --git a/tools/perf/util/mmap.c b/tools/perf/util/mmap.c
index fc832676a798..e53038d76445 100644
--- a/tools/perf/util/mmap.c
+++ b/tools/perf/util/mmap.c
@@ -155,6 +155,8 @@ void __weak auxtrace_mmap_params__set_idx(struct auxtrace_mmap_params *mp __mayb

void perf_mmap__munmap(struct perf_mmap *map)
{
+ if (map->data)
+ zfree(&map->data);
if (map->base != NULL) {
munmap(map->base, perf_mmap__mmap_len(map));
map->base = NULL;
@@ -166,6 +168,7 @@ void perf_mmap__munmap(struct perf_mmap *map)

int perf_mmap__mmap(struct perf_mmap *map, struct mmap_params *mp, int fd)
{
+ int delta_max;
/*
* The last one will be done at perf_mmap__consume(), so that we
* make sure we don't prevent tools from consuming every last event in
@@ -190,6 +193,28 @@ int perf_mmap__mmap(struct perf_mmap *map, struct mmap_params *mp, int fd)
map->base = NULL;
return -1;
}
+ delta_max = sysconf(_SC_AIO_PRIO_DELTA_MAX);
+ map->data = malloc(perf_mmap__mmap_len(map));
+ if (!map->data) {
+ pr_debug2("failed to allocate data buffer, error %d\n",
+ errno);
+ 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->cblock.aio_fildes = -1;
+ /*
+ * Allocate cblock with max priority delta to
+ * have faster aio_write() calls because queued
+ * requests are kept in separate per-prio queues
+ * and adding a new request iterates thru shorter
+ * per-prio list.
+ */
+ map->cblock.aio_reqprio = delta_max;
map->fd = fd;

if (auxtrace_mmap__mmap(&map->auxtrace_mmap,
diff --git a/tools/perf/util/mmap.h b/tools/perf/util/mmap.h
index d82294db1295..1974e621e36b 100644
--- a/tools/perf/util/mmap.h
+++ b/tools/perf/util/mmap.h
@@ -6,6 +6,7 @@
#include <linux/types.h>
#include <asm/barrier.h>
#include <stdbool.h>
+#include <aio.h>
#include "auxtrace.h"
#include "event.h"

@@ -25,6 +26,8 @@ struct perf_mmap {
bool overwrite;
struct auxtrace_mmap auxtrace_mmap;
char event_copy[PERF_SAMPLE_MAX_SIZE] __aligned(8);
+ void *data;
+ struct aiocb cblock;
};

/*