From: David Miller <[email protected]> Date: Sat, 10 Nov 2012 14:12:19 -0500 (EST)
Ping? > 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 <[email protected]> > > diff --git a/tools/perf/util/session.c b/tools/perf/util/session.c > index 8cdd232..2cd3cc3 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); > @@ -1369,6 +1360,18 @@ 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) > @@ -1376,7 +1379,7 @@ 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 page_size, mmap_size; > - char *buf, *mmaps[8]; > + char *buf, *mmaps[NUM_MMAPS]; > union perf_event *event; > uint32_t size; > > @@ -1393,7 +1396,7 @@ 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 dd64261..903966b 100644 > --- a/tools/perf/util/session.h > +++ b/tools/perf/util/session.h > @@ -29,7 +29,6 @@ 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; -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
