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* perf: commit 55b4462 causes perf record to hang
@ 2011-01-10 18:47 David Ahern
  2011-01-10 19:40 ` Arnaldo Carvalho de Melo
  2011-01-10 20:00 ` Arnaldo Carvalho de Melo
  0 siblings, 2 replies; 6+ messages in thread
From: David Ahern @ 2011-01-10 18:47 UTC (permalink / raw)
  To: Thomas Gleixner, Ingo Molnar, a.p.zijlstra, paulus,
	Arnaldo Carvalho de Melo, tzanussi, im
  Cc: linux-kernel, linux-perf-users

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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 <tglx@linutronix.de>
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

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diff --git a/tools/perf/util/session.c b/tools/perf/util/session.c
index 6fb4694..5d35e13 100644
--- a/tools/perf/util/session.c
+++ b/tools/perf/util/session.c
@@ -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;
 

^ permalink raw reply related	[flat|nested] 6+ messages in thread
end of thread, other threads:[~2011-01-11 11:35 UTC | newest]

Thread overview: 6+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2011-01-10 18:47 perf: commit 55b4462 causes perf record to hang David Ahern
2011-01-10 19:40 ` Arnaldo Carvalho de Melo
2011-01-10 20:00 ` Arnaldo Carvalho de Melo
2011-01-10 20:07   ` David Ahern
2011-01-11  8:28   ` Thomas Gleixner
2011-01-11 11:35     ` Arnaldo Carvalho de Melo

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