From 35d48ddfc0627443bd7ad2750a3f65d42cb742a0 Mon Sep 17 00:00:00 2001 From: David Miller Date: Sat, 10 Nov 2012 14:12:19 -0500 Subject: perf tools: Fix mmap limitations on 32-bit This is a suggested patch to fix the bug I reported at: http://marc.info/?l=linux-kernel&m=135033028924652&w=2 Essentially, there is a hard requirement that when perf analyzes a trace, it must have the entire thing mmap()'d. Therefore the scheme used on 32-bit where we have a fixed (8) number of 32MB mmaps, and cycle through them, simply does not work. One of the reasons this requirement exists is because the iterators maintain references to perf entry objects and those references don't just simply go away when this mmap code decides to cycle an old mmap area out and reuse it. At this point, those entry pointers now point to garbage resulting in unpredictable behavior and crashes. It is better to try to mmap() as much as we can and if we do actually run into address space limitations, the failure of the mmap() call will indicate that and stop processing. I noticed that perf_session->mmap_window is set to a constant in one location, and only used in one other location. So I got rid of it altogether. So we adjust the size of the mmaps[] array to the maximum we could need. On 64-bit we only need one slot. On 32-bit we could need up to 128 (128 * 32MB == 4GB). I've verified that this allows a large (~600MB) perf.data file to be analyzed properly with a 32-bit perf binary, which previously was not possible. Signed-off-by: David S. Miller Cc: Ingo Molnar Cc: Paul Mackerras Cc: Peter Zijlstra Link: http://lkml.kernel.org/r/20121110.141219.582924082787523608.davem@davemloft.net Signed-off-by: Arnaldo Carvalho de Melo --- tools/perf/util/session.c | 25 ++++++++++++++----------- tools/perf/util/session.h | 1 - 2 files changed, 14 insertions(+), 12 deletions(-) (limited to 'tools/perf') diff --git a/tools/perf/util/session.c b/tools/perf/util/session.c index d5fb60760bac..aa5e58255cba 100644 --- a/tools/perf/util/session.c +++ b/tools/perf/util/session.c @@ -128,15 +128,6 @@ struct perf_session *perf_session__new(const char *filename, int mode, goto out; memcpy(self->filename, filename, len); - /* - * 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->machines = RB_ROOT; self->repipe = repipe; INIT_LIST_HEAD(&self->ordered_samples.samples); @@ -1386,6 +1377,18 @@ fetch_mmaped_event(struct perf_session *session, return event; } +/* + * 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 +#define MMAP_SIZE ULLONG_MAX +#define NUM_MMAPS 1 +#else +#define MMAP_SIZE (32 * 1024 * 1024ULL) +#define NUM_MMAPS 128 +#endif + int __perf_session__process_events(struct perf_session *session, u64 data_offset, u64 data_size, u64 file_size, struct perf_tool *tool) @@ -1393,7 +1396,7 @@ int __perf_session__process_events(struct perf_session *session, u64 head, page_offset, file_offset, file_pos, progress_next; int err, mmap_prot, mmap_flags, map_idx = 0; size_t mmap_size; - char *buf, *mmaps[8]; + char *buf, *mmaps[NUM_MMAPS]; union perf_event *event; uint32_t size; @@ -1408,7 +1411,7 @@ int __perf_session__process_events(struct perf_session *session, progress_next = file_size / 16; - mmap_size = session->mmap_window; + mmap_size = MMAP_SIZE; if (mmap_size > file_size) mmap_size = file_size; diff --git a/tools/perf/util/session.h b/tools/perf/util/session.h index cea133a6bdf1..c18fabdff19b 100644 --- a/tools/perf/util/session.h +++ b/tools/perf/util/session.h @@ -30,7 +30,6 @@ struct ordered_samples { struct perf_session { struct perf_header header; unsigned long size; - unsigned long mmap_window; struct machine host_machine; struct rb_root machines; struct perf_evlist *evlist; -- cgit v1.2.1