perf: commit 55b4462 causes perf record to hang

With latest version of perf-core branch, a variant of perf record hangs:

# /tmp/build-perf/perf record -v -e cs -fo /tmp/perf.data  -- sleep 1
couldn't open /proc/-1/status
couldn't open /proc/-1/maps
[ perf record: Woken up 1 times to write data ]
[ perf record: Captured and wrote 0.003 MB /tmp/perf.data (~120 samples) ]

It sits there forever. Back trace is:

(gdb) bt
#0 0x0000000000447658 in __perf_session__process_events (session=0xab9500, data_offset=208,

    data_size=2896, file_size=3104, ops=0x685580) at util/session.c:1006
#1  0x00000000004107dd in process_buildids () at builtin-record.c:466
#2  0x000000000041084d in atexit_header () at builtin-record.c:477
#3  0x00007f45cc3e89e1 in exit () from /lib64/libc.so.6
#4  0x0000000000404749 in handle_internal_command (argc=9,

argv=0x7fffc59e2c70) at perf.c:359
#5 0x000000000040488e in run_argv (argcp=0x7fffc59e2b5c, argv=0x7fffc59e2b50) at perf.c:403
#6 0x0000000000404a98 in main (argc=9, argv=0x7fffc59e2c70) at perf.c:489

git bisect traced the hang to

commit 55b44629f599a2305265ae9c77f9d9bcfd6ddc17

Author: Thomas Gleixner <[email protected]>
Date:   Tue Nov 30 17:49:46 2010 +0000

perf session: Use sensible mmap size

On 64bit we can map the whole file in one go, on 32bit we can at
least map
32MB and not map/unmap tiny chunks of the file.

Base the progress bar on 1/16 of the data size.

Preparatory patch to get rid of the malloc/memcpy/free of trace data.

If I revert the changes (attached porting of it) perf-record does not hang.

David

tools/perf/util/session.c +13 -29

index 6fb4694..5d35e13 100644
@@ -143,15 +143,7 @@ struct perf_session *perf_session__new(const char *filename, int mode,
 	INIT_LIST_HEAD(&self->dead_threads);
 	self->hists_tree = RB_ROOT;
 	self->last_match = NULL;
-	/*
-	 * On 64bit we can mmap the data file in one go. No need for tiny mmap
-	 * slices. On 32bit we use 32MB.
-	 */
-#if BITS_PER_LONG == 64
-	self->mmap_window = ULLONG_MAX;
-#else
-	self->mmap_window = 32 * 1024 * 1024ULL;
-#endif
+	self->mmap_window = 32;
 	self->machines = RB_ROOT;
 	self->repipe = repipe;
 	INIT_LIST_HEAD(&self->ordered_samples.samples);

@@ -949,14 +941,19 @@ int __perf_session__process_events(struct perf_session *session,
 				   u64 data_offset, u64 data_size,
 				   u64 file_size, struct perf_event_ops *ops)
 {
-	u64 head, page_offset, file_offset, file_pos, progress_next;
+	u64 head, page_offset, file_offset, file_pos;
 	int err, mmap_prot, mmap_flags, map_idx = 0;
 	struct ui_progress *progress;
-	size_t	page_size, mmap_size;
+	size_t	page_size;
 	char *buf, *mmaps[8];
 	event_t *event;
 	uint32_t size;
 
+	progress = ui_progress__new("Processing events...", session->size);
+	if (progress == NULL)
+		return -1;
+
+
 	perf_event_ops__fill_defaults(ops);
 
 	page_size = sysconf(_SC_PAGESIZE);

@@ -968,15 +965,6 @@ int __perf_session__process_events(struct perf_session *session,
 	if (data_offset + data_size < file_size)
 		file_size = data_offset + data_size;
 
-	progress_next = file_size / 16;
-	progress = ui_progress__new("Processing events...", file_size);
-	if (progress == NULL)
-		return -1;
-
-	mmap_size = session->mmap_window;
-	if (mmap_size > file_size)
-		mmap_size = file_size;
-
 	memset(mmaps, 0, sizeof(mmaps));
 
 	mmap_prot  = PROT_READ;

@@ -987,13 +975,14 @@ int __perf_session__process_events(struct perf_session *session,
 		mmap_flags = MAP_PRIVATE;
 	}
 remap:
-	buf = mmap(NULL, mmap_size, mmap_prot, mmap_flags, session->fd,
-		   file_offset);
+	buf = mmap(NULL, page_size * session->mmap_window, mmap_prot,
+		   mmap_flags, session->fd, file_offset);
 	if (buf == MAP_FAILED) {
 		pr_err("failed to mmap file\n");
 		err = -errno;
 		goto out_err;
 	}
+	ui_progress__update(progress, file_offset);
 	mmaps[map_idx] = buf;
 	map_idx = (map_idx + 1) & (ARRAY_SIZE(mmaps) - 1);
 	file_pos = file_offset + head;

@@ -1007,9 +996,9 @@ more:
 	if (size == 0)
 		size = 8;
 
-	if (head + event->header.size >= mmap_size) {
+	if (head + event->header.size >= page_size * session->mmap_window) {
 		if (mmaps[map_idx]) {
-			munmap(mmaps[map_idx], mmap_size);
+			munmap(mmaps[map_idx], page_size * session->mmap_window);
 			mmaps[map_idx] = NULL;
 		}
 

@@ -1039,11 +1028,6 @@ more:
 	head += size;
 	file_pos += size;
 
-	if (file_pos >= progress_next) {
-		progress_next += file_size / 16;
-		ui_progress__update(progress, file_pos);
-	}
-
 	if (file_pos < file_size)
 		goto more;
 

With latest version of perf-core branch, a variant of perf record hangs:

# /tmp/build-perf/perf record -v -e cs -fo /tmp/perf.data  -- sleep 1
[ perf record: Captured and wrote 0.003 MB /tmp/perf.data (~120 samples) ]

It sits there forever. Back trace is:

(gdb) bt

#0  0x0000000000447658 in __perf_session__process_events (session=0xab9500, data_offset=208, data_size=2896, file_size=3104, ops=0x685580) at util/session.c:1006
#1  0x00000000004107dd in process_buildids () at builtin-record.c:466
#2  0x000000000041084d in atexit_header () at builtin-record.c:477

git bisect traced the hang to

commit 55b44629f599a2305265ae9c77f9d9bcfd6ddc17

Author: Thomas Gleixner <[email protected]>
Date:   Tue Nov 30 17:49:46 2010 +0000

Em Mon, Jan 10, 2011 at 11:47:43AM -0700, David Ahern escreveu:

Quoted 11 lines

With latest version of perf-core branch, a variant of perf record hangs:

# /tmp/build-perf/perf record -v -e cs -fo /tmp/perf.data  -- sleep 1
[ perf record: Captured and wrote 0.003 MB /tmp/perf.data (~120 samples) ]

It sits there forever. Back trace is:

(gdb) bt

#0  0x0000000000447658 in __perf_session__process_events (session=0xab9500, data_offset=208, data_size=2896, file_size=3104, ops=0x685580) at util/session.c:1006
#1  0x00000000004107dd in process_buildids () at builtin-record.c:466
#2  0x000000000041084d in atexit_header () at builtin-record.c:477

Quoted 5 lines

git bisect traced the hang to

commit 55b44629f599a2305265ae9c77f9d9bcfd6ddc17

Author: Thomas Gleixner <[email protected]>
Date:   Tue Nov 30 17:49:46 2010 +0000

Can you try with this patch, not reverting tglx's patch?

tools/perf/util/session.c +0 -0

index 6fb4694..313dac2 100644

--
To unsubscribe from this list: send the line "unsubscribe linux-perf-users" in the body of a message to [email protected]
More majordomo info at http://vger.kernel.org/majordomo-info.html

Em Mon, Jan 10, 2011 at 11:47:43AM -0700, David Ahern escreveu:

Quoted 11 lines

With latest version of perf-core branch, a variant of perf record hangs:

# /tmp/build-perf/perf record -v -e cs -fo /tmp/perf.data  -- sleep 1
[ perf record: Captured and wrote 0.003 MB /tmp/perf.data (~120 samples) ]

It sits there forever. Back trace is:

(gdb) bt

#0  0x0000000000447658 in __perf_session__process_events (session=0xab9500, data_offset=208, data_size=2896, file_size=3104, ops=0x685580) at util/session.c:1006
#1  0x00000000004107dd in process_buildids () at builtin-record.c:466
#2  0x000000000041084d in atexit_header () at builtin-record.c:477

Quoted 5 lines

git bisect traced the hang to

commit 55b44629f599a2305265ae9c77f9d9bcfd6ddc17

Author: Thomas Gleixner <[email protected]>
Date:   Tue Nov 30 17:49:46 2010 +0000

Can you try with this patch, not reverting tglx's patch?

tools/perf/util/session.c +0 -0

index 6fb4694..313dac2 100644

Quoted 10 lines

Can you try with this patch, not reverting tglx's patch?

tools/perf/util/session.c +0 -0

index 6fb4694..313dac2 100644
@@ -1007,7 +1007,7 @@ more:
 	if (size == 0)
 		size = 8;
 

tools/perf/util/session.c more: · line 1013

Quoted 6 lines

tools/perf/util/session.c +1 -1

-	if (head + event->header.size >= mmap_size) {
+	if (head + event->header.size > mmap_size) {
 		if (mmaps[map_idx]) {
 			munmap(mmaps[map_idx], mmap_size);
 			mmaps[map_idx] = NULL;

/me feels stupid