When libunwind tries to resolve callchains it needs to know the offset of .eh_frame_hdr or .debug_frame to access the dso. Since it calls dso__data_fd(), it'll try to grab dso->lock everytime for same information. So save it to dso_data struct and reuse it.
Note that there's a window between dso__data_fd() and actual use of the fd. The fd could be closed by other threads to deal with the open file limit in dso cache code. But I think it's ok since in that case elf_section_offset() will return 0 so it'll be tried in next acess. Signed-off-by: Namhyung Kim <namhy...@kernel.org> --- tools/perf/util/dso.h | 1 + tools/perf/util/unwind-libunwind.c | 31 ++++++++++++++++++++----------- 2 files changed, 21 insertions(+), 11 deletions(-) diff --git a/tools/perf/util/dso.h b/tools/perf/util/dso.h index 28e8bb320495..5cf8dfe04eac 100644 --- a/tools/perf/util/dso.h +++ b/tools/perf/util/dso.h @@ -143,6 +143,7 @@ struct dso { u32 status_seen; size_t file_size; struct list_head open_entry; + u64 frame_offset; } data; union { /* Tool specific area */ diff --git a/tools/perf/util/unwind-libunwind.c b/tools/perf/util/unwind-libunwind.c index 94929ec491f3..3cb78c36faad 100644 --- a/tools/perf/util/unwind-libunwind.c +++ b/tools/perf/util/unwind-libunwind.c @@ -244,14 +244,17 @@ static int read_unwind_spec_eh_frame(struct dso *dso, struct machine *machine, u64 *fde_count) { int ret = -EINVAL, fd; - u64 offset; + u64 offset = dso->data.frame_offset; - fd = dso__data_fd(dso, machine); - if (fd < 0) - return -EINVAL; + if (offset == 0) { + fd = dso__data_fd(dso, machine); + if (fd < 0) + return -EINVAL; - /* Check the .eh_frame section for unwinding info */ - offset = elf_section_offset(fd, ".eh_frame_hdr"); + /* Check the .eh_frame section for unwinding info */ + offset = elf_section_offset(fd, ".eh_frame_hdr"); + dso->data.frame_offset = offset; + } if (offset) ret = unwind_spec_ehframe(dso, machine, offset, @@ -265,14 +268,20 @@ static int read_unwind_spec_eh_frame(struct dso *dso, struct machine *machine, static int read_unwind_spec_debug_frame(struct dso *dso, struct machine *machine, u64 *offset) { - int fd = dso__data_fd(dso, machine); + int fd; + u64 ofs = dso->data.frame_offset; - if (fd < 0) - return -EINVAL; + if (ofs == 0) { + fd = dso__data_fd(dso, machine); + if (fd < 0) + return -EINVAL; - /* Check the .debug_frame section for unwinding info */ - *offset = elf_section_offset(fd, ".debug_frame"); + /* Check the .debug_frame section for unwinding info */ + ofs = elf_section_offset(fd, ".debug_frame"); + dso->data.frame_offset = ofs; + } + *offset = ofs; if (*offset) return 0; -- 2.1.3 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/