[PATCH 3/5] perf tool: Introducing perf_mmap object

From: Jiri Olsa
Date: Fri Nov 18 2011 - 08:47:38 EST

Adding perf_mmap object to handle event memory maps.

All the memory map related functions originally scatered through
the whole code arenow place in perf_mmap object.

To map and unmap perf_mmap:
perf_mmap__open
perf_mmap__close

For reading events via callback:
perf_mmap__process

For reading events directly:
perf_mmap__read

following helpers were moved in from perf.h:
perf_mmap__read_head
perf_mmap__write_tail

Signed-off-by: Jiri Olsa <jolsa@xxxxxxxxxx>
---
tools/perf/Makefile | 2 +
tools/perf/builtin-record.c | 57 ++++-------------
tools/perf/builtin-test.c | 6 ++-
tools/perf/builtin-top.c | 19 ++++--
tools/perf/perf.h | 26 --------
tools/perf/util/evlist.c | 117 +++++++-----------------------------
tools/perf/util/evlist.h | 2 +-
tools/perf/util/mmap.c | 138 +++++++++++++++++++++++++++++++++++++++++++
tools/perf/util/mmap.h | 45 ++++++++++++++
9 files changed, 239 insertions(+), 173 deletions(-)
create mode 100644 tools/perf/util/mmap.c
create mode 100644 tools/perf/util/mmap.h

diff --git a/tools/perf/Makefile b/tools/perf/Makefile
index b98e307..0158b66 100644
--- a/tools/perf/Makefile
+++ b/tools/perf/Makefile
@@ -274,6 +274,7 @@ LIB_H += util/xyarray.h
LIB_H += util/header.h
LIB_H += util/help.h
LIB_H += util/session.h
+LIB_H += util/mmap.h
LIB_H += util/strbuf.h
LIB_H += util/strlist.h
LIB_H += util/strfilter.h
@@ -337,6 +338,7 @@ LIB_OBJS += $(OUTPUT)util/debug.o
LIB_OBJS += $(OUTPUT)util/map.o
LIB_OBJS += $(OUTPUT)util/pstack.o
LIB_OBJS += $(OUTPUT)util/session.o
+LIB_OBJS += $(OUTPUT)util/mmap.o
LIB_OBJS += $(OUTPUT)util/thread.o
LIB_OBJS += $(OUTPUT)util/thread_map.o
LIB_OBJS += $(OUTPUT)util/trace-event-parse.o
diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
index 1132e70..89b3dc2 100644
--- a/tools/perf/builtin-record.c
+++ b/tools/perf/builtin-record.c
@@ -25,6 +25,7 @@
#include "util/symbol.h"
#include "util/cpumap.h"
#include "util/thread_map.h"
+#include "util/mmap.h"

#include <unistd.h>
#include <sched.h>
@@ -65,7 +66,6 @@ static bool no_buildid = false;
static bool no_buildid_cache = false;
static struct perf_evlist *evsel_list;

-static long samples = 0;
static u64 bytes_written = 0;

static int file_new = 1;
@@ -103,39 +103,6 @@ static int process_synthesized_event(union perf_event *event,
return 0;
}

-static void mmap_read(struct perf_mmap *md)
-{
- unsigned int head = perf_mmap__read_head(md);
- unsigned int old = md->prev;
- unsigned char *data = md->base + page_size;
- unsigned long size;
- void *buf;
-
- if (old == head)
- return;
-
- samples++;
-
- size = head - old;
-
- if ((old & md->mask) + size != (head & md->mask)) {
- buf = &data[old & md->mask];
- size = md->mask + 1 - (old & md->mask);
- old += size;
-
- write_output(buf, size);
- }
-
- buf = &data[old & md->mask];
- size = head - old;
- old += size;
-
- write_output(buf, size);
-
- md->prev = old;
- perf_mmap__write_tail(md, old);
-}
-
static volatile int done = 0;
static volatile int signr = -1;
static volatile int child_finished = 0;
@@ -442,17 +409,25 @@ static struct perf_event_header finished_round_event = {
.type = PERF_RECORD_FINISHED_ROUND,
};

-static void mmap_read_all(void)
+static void mmap_read(struct perf_mmap *m __used, void *buf, unsigned long size)
+{
+ write_output(buf, size);
+}
+
+static int mmap_read_all(void)
{
- int i;
+ int i, ret = 0;

for (i = 0; i < evsel_list->nr_mmaps; i++) {
- if (evsel_list->mmap[i].base)
- mmap_read(&evsel_list->mmap[i]);
+ struct perf_mmap *m = &evsel_list->mmap[i];
+ if (m->base)
+ ret += perf_mmap__process(m, mmap_read);
}

if (perf_header__has_feat(&session->header, HEADER_TRACE_INFO))
write_output(&finished_round_event, sizeof(finished_round_event));
+
+ return ret;
}

static int __cmd_record(int argc, const char **argv)
@@ -712,11 +687,7 @@ static int __cmd_record(int argc, const char **argv)
close(go_pipe[1]);

for (;;) {
- int hits = samples;
-
- mmap_read_all();
-
- if (hits == samples) {
+ if (!mmap_read_all()) {
if (done)
break;
err = poll(evsel_list->pollfd, evsel_list->nr_fds, -1);
diff --git a/tools/perf/builtin-test.c b/tools/perf/builtin-test.c
index 831d1ba..feb3218 100644
--- a/tools/perf/builtin-test.c
+++ b/tools/perf/builtin-test.c
@@ -12,6 +12,7 @@
#include "util/parse-events.h"
#include "util/symbol.h"
#include "util/thread_map.h"
+#include "util/mmap.h"
#include "../../include/linux/hw_breakpoint.h"

static long page_size;
@@ -476,6 +477,7 @@ static int test__basic_mmap(void)
expected_nr_events[nsyscalls], i, j;
struct perf_evsel *evsels[nsyscalls], *evsel;
int sample_size = __perf_evsel__sample_size(attr.sample_type);
+ struct perf_mmap *md;

for (i = 0; i < nsyscalls; ++i) {
char name[64];
@@ -551,7 +553,9 @@ static int test__basic_mmap(void)
++foo;
}

- while ((event = perf_evlist__mmap_read(evlist, 0)) != NULL) {
+ md = &evlist->mmap[0];
+
+ while ((event = perf_mmap__read(md)) != NULL) {
struct perf_sample sample;

if (event->header.type != PERF_RECORD_SAMPLE) {
diff --git a/tools/perf/builtin-top.c b/tools/perf/builtin-top.c
index 8e02027..032f70d 100644
--- a/tools/perf/builtin-top.c
+++ b/tools/perf/builtin-top.c
@@ -38,6 +38,7 @@
#include "util/cpumap.h"
#include "util/xyarray.h"
#include "util/sort.h"
+#include "util/mmap.h"

#include "util/debug.h"

@@ -804,14 +805,16 @@ static void perf_event__process_sample(const union perf_event *event,
return;
}

-static void perf_session__mmap_read_idx(struct perf_session *self, int idx)
+static void session_mmap_read(struct perf_session *self,
+ struct perf_mmap *md)
{
- struct perf_sample sample;
- struct perf_evsel *evsel;
union perf_event *event;
- int ret;

- while ((event = perf_evlist__mmap_read(top.evlist, idx)) != NULL) {
+ while ((event = perf_mmap__read(md)) != NULL) {
+ struct perf_sample sample;
+ struct perf_evsel *evsel;
+ int ret;
+
ret = perf_session__parse_sample(self, event, &sample);
if (ret) {
pr_err("Can't parse sample, err = %d\n", ret);
@@ -835,8 +838,10 @@ static void perf_session__mmap_read(struct perf_session *self)
{
int i;

- for (i = 0; i < top.evlist->nr_mmaps; i++)
- perf_session__mmap_read_idx(self, i);
+ for (i = 0; i < top.evlist->nr_mmaps; i++) {
+ struct perf_mmap *md = &top.evlist->mmap[i];
+ session_mmap_read(self, md);
+ }
}

static void start_counters(struct perf_evlist *evlist)
diff --git a/tools/perf/perf.h b/tools/perf/perf.h
index 914c895..d79efbb 100644
--- a/tools/perf/perf.h
+++ b/tools/perf/perf.h
@@ -104,32 +104,6 @@ void get_term_dimensions(struct winsize *ws);
#include "util/types.h"
#include <stdbool.h>

-struct perf_mmap {
- void *base;
- int mask;
- unsigned int prev;
-};
-
-static inline unsigned int perf_mmap__read_head(struct perf_mmap *mm)
-{
- struct perf_event_mmap_page *pc = mm->base;
- int head = pc->data_head;
- rmb();
- return head;
-}
-
-static inline void perf_mmap__write_tail(struct perf_mmap *md,
- unsigned long tail)
-{
- struct perf_event_mmap_page *pc = md->base;
-
- /*
- * ensure all reads are done before we write the tail out.
- */
- /* mb(); */
- pc->data_tail = tail;
-}
-
/*
* prctl(PR_TASK_PERF_EVENTS_DISABLE) will (cheaply) disable all
* counters in the current task.
diff --git a/tools/perf/util/evlist.c b/tools/perf/util/evlist.c
index 0f715d0..2237833 100644
--- a/tools/perf/util/evlist.c
+++ b/tools/perf/util/evlist.c
@@ -12,6 +12,7 @@
#include "evlist.h"
#include "evsel.h"
#include "util.h"
+#include "mmap.h"

#include <sys/mman.h>

@@ -200,82 +201,14 @@ struct perf_evsel *perf_evlist__id2evsel(struct perf_evlist *evlist, u64 id)
return NULL;
}

-union perf_event *perf_evlist__mmap_read(struct perf_evlist *evlist, int idx)
-{
- /* XXX Move this to perf.c, making it generally available */
- unsigned int page_size = sysconf(_SC_PAGE_SIZE);
- struct perf_mmap *md = &evlist->mmap[idx];
- unsigned int head = perf_mmap__read_head(md);
- unsigned int old = md->prev;
- unsigned char *data = md->base + page_size;
- union perf_event *event = NULL;
-
- if (evlist->overwrite) {
- /*
- * If we're further behind than half the buffer, there's a chance
- * the writer will bite our tail and mess up the samples under us.
- *
- * If we somehow ended up ahead of the head, we got messed up.
- *
- * In either case, truncate and restart at head.
- */
- int diff = head - old;
- if (diff > md->mask / 2 || diff < 0) {
- fprintf(stderr, "WARNING: failed to keep up with mmap data.\n");
-
- /*
- * head points to a known good entry, start there.
- */
- old = head;
- }
- }
-
- if (old != head) {
- size_t size;
-
- event = (union perf_event *)&data[old & md->mask];
- size = event->header.size;
-
- /*
- * Event straddles the mmap boundary -- header should always
- * be inside due to u64 alignment of output.
- */
- if ((old & md->mask) + size != ((old + size) & md->mask)) {
- unsigned int offset = old;
- unsigned int len = min(sizeof(*event), size), cpy;
- void *dst = &evlist->event_copy;
-
- do {
- cpy = min(md->mask + 1 - (offset & md->mask), len);
- memcpy(dst, &data[offset & md->mask], cpy);
- offset += cpy;
- dst += cpy;
- len -= cpy;
- } while (len);
-
- event = &evlist->event_copy;
- }
-
- old += size;
- }
-
- md->prev = old;
-
- if (!evlist->overwrite)
- perf_mmap__write_tail(md, old);
-
- return event;
-}
-
void perf_evlist__munmap(struct perf_evlist *evlist)
{
int i;

for (i = 0; i < evlist->nr_mmaps; i++) {
- if (evlist->mmap[i].base != NULL) {
- munmap(evlist->mmap[i].base, evlist->mmap_len);
- evlist->mmap[i].base = NULL;
- }
+ struct perf_mmap *m = &evlist->mmap[i];
+ if (m->base != NULL)
+ perf_mmap__close(m);
}

free(evlist->mmap);
@@ -292,20 +225,18 @@ int perf_evlist__alloc_mmap(struct perf_evlist *evlist)
}

static int __perf_evlist__mmap(struct perf_evlist *evlist,
- int idx, int prot, int mask, int fd)
+ int idx, int fd)
{
- evlist->mmap[idx].prev = 0;
- evlist->mmap[idx].mask = mask;
- evlist->mmap[idx].base = mmap(NULL, evlist->mmap_len, prot,
- MAP_SHARED, fd, 0);
- if (evlist->mmap[idx].base == MAP_FAILED)
+ struct perf_mmap *m = &evlist->mmap[idx];
+
+ if (perf_mmap__open(m, fd, evlist->overwrite, evlist->pages))
return -1;

perf_evlist__add_pollfd(evlist, fd);
return 0;
}

-static int perf_evlist__mmap_per_cpu(struct perf_evlist *evlist, int prot, int mask)
+static int perf_evlist__mmap_per_cpu(struct perf_evlist *evlist)
{
struct perf_evsel *evsel;
int cpu, thread;
@@ -320,7 +251,7 @@ static int perf_evlist__mmap_per_cpu(struct perf_evlist *evlist, int prot, int m
if (output == -1) {
output = fd;
if (__perf_evlist__mmap(evlist, cpu,
- prot, mask, output) < 0)
+ output) < 0)
goto out_unmap;
} else {
if (ioctl(fd, PERF_EVENT_IOC_SET_OUTPUT, output) != 0)
@@ -334,15 +265,14 @@ static int perf_evlist__mmap_per_cpu(struct perf_evlist *evlist, int prot, int m

out_unmap:
for (cpu = 0; cpu < evlist->cpus->nr; cpu++) {
- if (evlist->mmap[cpu].base != NULL) {
- munmap(evlist->mmap[cpu].base, evlist->mmap_len);
- evlist->mmap[cpu].base = NULL;
- }
+ struct perf_mmap *m = &evlist->mmap[cpu];
+ if (m->base != NULL)
+ perf_mmap__close(m);
}
return -1;
}

-static int perf_evlist__mmap_per_thread(struct perf_evlist *evlist, int prot, int mask)
+static int perf_evlist__mmap_per_thread(struct perf_evlist *evlist)
{
struct perf_evsel *evsel;
int thread;
@@ -356,7 +286,7 @@ static int perf_evlist__mmap_per_thread(struct perf_evlist *evlist, int prot, in
if (output == -1) {
output = fd;
if (__perf_evlist__mmap(evlist, thread,
- prot, mask, output) < 0)
+ output) < 0)
goto out_unmap;
} else {
if (ioctl(fd, PERF_EVENT_IOC_SET_OUTPUT, output) != 0)
@@ -369,10 +299,9 @@ static int perf_evlist__mmap_per_thread(struct perf_evlist *evlist, int prot, in

out_unmap:
for (thread = 0; thread < evlist->threads->nr; thread++) {
- if (evlist->mmap[thread].base != NULL) {
- munmap(evlist->mmap[thread].base, evlist->mmap_len);
- evlist->mmap[thread].base = NULL;
- }
+ struct perf_mmap *m = &evlist->mmap[thread];
+ if (m->base != NULL)
+ perf_mmap__close(m);
}
return -1;
}
@@ -421,10 +350,8 @@ static int perf_evlist__init_ids(struct perf_evlist *evlist)
*/
int perf_evlist__mmap(struct perf_evlist *evlist, int pages, bool overwrite)
{
- unsigned int page_size = sysconf(_SC_PAGE_SIZE);
- int mask = pages * page_size - 1, ret;
const struct cpu_map *cpus = evlist->cpus;
- int prot = PROT_READ | (overwrite ? 0 : PROT_WRITE);
+ int ret;

if (evlist->mmap == NULL && perf_evlist__alloc_mmap(evlist) < 0)
return -ENOMEM;
@@ -433,16 +360,16 @@ int perf_evlist__mmap(struct perf_evlist *evlist, int pages, bool overwrite)
return -ENOMEM;

evlist->overwrite = overwrite;
- evlist->mmap_len = (pages + 1) * page_size;
+ evlist->pages = pages;

ret = perf_evlist__init_ids(evlist);
if (ret)
return ret;

if (cpus->map[0] == -1)
- return perf_evlist__mmap_per_thread(evlist, prot, mask);
+ return perf_evlist__mmap_per_thread(evlist);

- return perf_evlist__mmap_per_cpu(evlist, prot, mask);
+ return perf_evlist__mmap_per_cpu(evlist);
}

int perf_evlist__create_maps(struct perf_evlist *evlist, pid_t target_pid,
diff --git a/tools/perf/util/evlist.h b/tools/perf/util/evlist.h
index 1779ffe..3784273 100644
--- a/tools/perf/util/evlist.h
+++ b/tools/perf/util/evlist.h
@@ -18,7 +18,7 @@ struct perf_evlist {
int nr_entries;
int nr_fds;
int nr_mmaps;
- int mmap_len;
+ int pages;
bool overwrite;
union perf_event event_copy;
struct perf_mmap *mmap;
diff --git a/tools/perf/util/mmap.c b/tools/perf/util/mmap.c
new file mode 100644
index 0000000..45e62a2
--- /dev/null
+++ b/tools/perf/util/mmap.c
@@ -0,0 +1,138 @@
+#include <string.h>
+#include <stdio.h>
+#include "mmap.h"
+
+int perf_mmap__open(struct perf_mmap *m, int fd, bool overwrite, int pages)
+{
+ unsigned int page_size = sysconf(_SC_PAGE_SIZE);
+ int mask, len, prot;
+ void *base;
+
+ mask = pages * page_size - 1;
+ len = (pages + 1) * page_size;
+ prot = PROT_READ | (overwrite ? 0 : PROT_WRITE);
+
+ base = mmap(NULL, len, prot, MAP_SHARED, fd, 0);
+ if (base == MAP_FAILED)
+ return -1;
+
+ memset(m, 0, sizeof(*m));
+ m->mask = mask;
+ m->len = len;
+ m->base = base;
+ m->fd = fd;
+ m->owrt = overwrite;
+ return 0;
+}
+
+int perf_mmap__close(struct perf_mmap *m)
+{
+ int ret = munmap(m->base, m->len);
+
+ memset(m, 0x0, sizeof(*m));
+ return ret;
+}
+
+int perf_mmap__process(struct perf_mmap *md, perf_mmap_process_t process)
+{
+ unsigned int head, old, page_size = sysconf(_SC_PAGE_SIZE);
+ unsigned char *data = md->base + page_size;
+ unsigned long size;
+ void *buf;
+
+ head = perf_mmap__read_head(md);
+ old = md->prev;
+
+ if (old == head)
+ return 0;
+
+ size = head - old;
+
+ if ((old & md->mask) + size != (head & md->mask)) {
+ buf = &data[old & md->mask];
+ size = md->mask + 1 - (old & md->mask);
+ old += size;
+
+ process(md, buf, size);
+ }
+
+ buf = &data[old & md->mask];
+ size = head - old;
+ old += size;
+
+ process(md, buf, size);
+
+ md->prev = old;
+ perf_mmap__write_tail(md, old);
+ return 1;
+}
+
+union perf_event *perf_mmap__read(struct perf_mmap *md)
+{
+ unsigned int head, old, page_size = sysconf(_SC_PAGE_SIZE);
+ unsigned char *data = md->base + page_size;
+ union perf_event *event = NULL;
+
+ head = perf_mmap__read_head(md);
+ old = md->prev;
+
+ if (md->owrt) {
+ /*
+ * If we're further behind than half the buffer, there's
+ * a chance the writer will bite our tail and mess up the
+ * samples under us.
+ *
+ * If we somehow ended up ahead of the head, we got messed up.
+ *
+ * In either case, truncate and restart at head.
+ */
+ int diff = head - old;
+ if (diff > md->mask / 2 || diff < 0) {
+ fprintf(stderr, "WARNING: failed to keep up "
+ "with mmap data.\n");
+
+ /*
+ * head points to a known good entry, start there.
+ */
+ old = head;
+ }
+ }
+
+ if (old != head) {
+ size_t size;
+
+ event = (union perf_event *)&data[old & md->mask];
+ size = event->header.size;
+
+ /*
+ * Event straddles the mmap boundary -- header should always
+ * be inside due to u64 alignment of output.
+ */
+ if ((old & md->mask) + size != ((old + size) & md->mask)) {
+ unsigned int offset = old;
+ unsigned int len = min(sizeof(*event), size), cpy;
+ static union perf_event event_copy;
+ void *dst = &event_copy;
+
+ do {
+ cpy = min(md->mask + 1 - (offset & md->mask),
+ len);
+ memcpy(dst, &data[offset & md->mask], cpy);
+ offset += cpy;
+ dst += cpy;
+ len -= cpy;
+ } while (len);
+
+ event = &event_copy;
+ }
+
+ old += size;
+ }
+
+ md->prev = old;
+
+ if (!md->owrt)
+ perf_mmap__write_tail(md, old);
+
+ return event;
+}
diff --git a/tools/perf/util/mmap.h b/tools/perf/util/mmap.h
new file mode 100644
index 0000000..24cf88f
--- /dev/null
+++ b/tools/perf/util/mmap.h
@@ -0,0 +1,45 @@
+#ifndef __PERF_MMAP_H
+#define __PERF_MMAP_H
+
+#include <sys/mman.h>
+#include "event.h"
+#include "../perf.h"
+
+struct perf_mmap {
+ void *base;
+ int mask;
+ u_int prev;
+ int len;
+ int fd;
+ bool owrt;
+};
+
+typedef void (*perf_mmap_process_t)(struct perf_mmap *m,
+ void *buf, unsigned long size);
+
+int perf_mmap__open(struct perf_mmap *m, int fd, bool overwrite, int pages);
+int perf_mmap__close(struct perf_mmap *m);
+int perf_mmap__process(struct perf_mmap *m, perf_mmap_process_t process);
+union perf_event *perf_mmap__read(struct perf_mmap *md);
+
+static inline unsigned int perf_mmap__read_head(struct perf_mmap *mm)
+{
+ struct perf_event_mmap_page *pc = mm->base;
+ int head = pc->data_head;
+ rmb();
+ return head;
+}
+
+static inline void perf_mmap__write_tail(struct perf_mmap *md,
+ unsigned long tail)
+{
+ struct perf_event_mmap_page *pc = md->base;
+
+ /*
+ * ensure all reads are done before we write the tail out.
+ */
+ /* mb(); */
+ pc->data_tail = tail;
+}
+
+#endif /* __PERF_MMAP_H */
--
1.7.4

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