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authorWang Nan <wangnan0@huawei.com>2016-05-23 07:13:41 +0000
committerArnaldo Carvalho de Melo <acme@redhat.com>2016-05-23 18:22:48 -0300
commit3a62a7b8200a177ad96161e4f2678514e6ee301e (patch)
treeb990cb212929775c1dc926ebc992dee6bbe7c03f /tools
parent09fa4f401296f555afb6f2f4282717644d94722e (diff)
downloadlinux-3a62a7b8200a177ad96161e4f2678514e6ee301e.tar.gz
perf record: Read from backward ring buffer
Introduce rb_find_range() to find start and end position from a backward ring buffer. Signed-off-by: Wang Nan <wangnan0@huawei.com> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Zefan Li <lizefan@huawei.com> Cc: pi3orama@163.com Link: http://lkml.kernel.org/r/1463987628-163563-5-git-send-email-wangnan0@huawei.com Signed-off-by: He Kuang <hekuang@huawei.com> Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Diffstat (limited to 'tools')
-rw-r--r--tools/perf/builtin-record.c52
-rw-r--r--tools/perf/util/evlist.c1
-rw-r--r--tools/perf/util/evlist.h1
3 files changed, 54 insertions, 0 deletions
diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
index 73ce651c84f6..dc3fcb597e4c 100644
--- a/tools/perf/builtin-record.c
+++ b/tools/perf/builtin-record.c
@@ -83,6 +83,54 @@ static int process_synthesized_event(struct perf_tool *tool,
return record__write(rec, event, event->header.size);
}
+static int
+backward_rb_find_range(void *buf, int mask, u64 head, u64 *start, u64 *end)
+{
+ struct perf_event_header *pheader;
+ u64 evt_head = head;
+ int size = mask + 1;
+
+ pr_debug2("backward_rb_find_range: buf=%p, head=%"PRIx64"\n", buf, head);
+ pheader = (struct perf_event_header *)(buf + (head & mask));
+ *start = head;
+ while (true) {
+ if (evt_head - head >= (unsigned int)size) {
+ pr_debug("Finshed reading backward ring buffer: rewind\n");
+ if (evt_head - head > (unsigned int)size)
+ evt_head -= pheader->size;
+ *end = evt_head;
+ return 0;
+ }
+
+ pheader = (struct perf_event_header *)(buf + (evt_head & mask));
+
+ if (pheader->size == 0) {
+ pr_debug("Finshed reading backward ring buffer: get start\n");
+ *end = evt_head;
+ return 0;
+ }
+
+ evt_head += pheader->size;
+ pr_debug3("move evt_head: %"PRIx64"\n", evt_head);
+ }
+ WARN_ONCE(1, "Shouldn't get here\n");
+ return -1;
+}
+
+static int
+rb_find_range(struct perf_evlist *evlist,
+ void *data, int mask, u64 head, u64 old,
+ u64 *start, u64 *end)
+{
+ if (!evlist->backward) {
+ *start = old;
+ *end = head;
+ return 0;
+ }
+
+ return backward_rb_find_range(data, mask, head, start, end);
+}
+
static int record__mmap_read(struct record *rec, int idx)
{
struct perf_mmap *md = &rec->evlist->mmap[idx];
@@ -94,6 +142,10 @@ static int record__mmap_read(struct record *rec, int idx)
void *buf;
int rc = 0;
+ if (rb_find_range(rec->evlist, data, md->mask, head,
+ old, &start, &end))
+ return -1;
+
if (start == end)
return 0;
diff --git a/tools/perf/util/evlist.c b/tools/perf/util/evlist.c
index 904523a2be90..e82ba90cc969 100644
--- a/tools/perf/util/evlist.c
+++ b/tools/perf/util/evlist.c
@@ -44,6 +44,7 @@ void perf_evlist__init(struct perf_evlist *evlist, struct cpu_map *cpus,
perf_evlist__set_maps(evlist, cpus, threads);
fdarray__init(&evlist->pollfd, 64);
evlist->workload.pid = -1;
+ evlist->backward = false;
}
struct perf_evlist *perf_evlist__new(void)
diff --git a/tools/perf/util/evlist.h b/tools/perf/util/evlist.h
index 97090b70976d..d740fb877ab6 100644
--- a/tools/perf/util/evlist.h
+++ b/tools/perf/util/evlist.h
@@ -44,6 +44,7 @@ struct perf_evlist {
bool overwrite;
bool enabled;
bool has_user_cpus;
+ bool backward;
size_t mmap_len;
int id_pos;
int is_pos;