From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754192AbbA2IK6 (ORCPT ); Thu, 29 Jan 2015 03:10:58 -0500 Received: from LGEMRELSE6Q.lge.com ([156.147.1.121]:51669 "EHLO lgemrelse6q.lge.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753553AbbA2IKV (ORCPT ); Thu, 29 Jan 2015 03:10:21 -0500 X-Original-SENDERIP: 10.177.220.203 X-Original-MAILFROM: namhyung@kernel.org From: Namhyung Kim To: Arnaldo Carvalho de Melo Cc: Ingo Molnar , Peter Zijlstra , Jiri Olsa , LKML , David Ahern , Adrian Hunter , Andi Kleen , Stephane Eranian , Frederic Weisbecker Subject: [PATCH 40/42] perf callchain: Save eh/debug frame offset for dwarf unwind Date: Thu, 29 Jan 2015 17:07:21 +0900 Message-Id: <1422518843-25818-41-git-send-email-namhyung@kernel.org> X-Mailer: git-send-email 2.2.2 In-Reply-To: <1422518843-25818-1-git-send-email-namhyung@kernel.org> References: <1422518843-25818-1-git-send-email-namhyung@kernel.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 --- 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 c18fcc0e8081..323ee08d56fc 100644 --- a/tools/perf/util/dso.h +++ b/tools/perf/util/dso.h @@ -141,6 +141,7 @@ 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 7ed6eaf232b6..3219b20837b5 100644 --- a/tools/perf/util/unwind-libunwind.c +++ b/tools/perf/util/unwind-libunwind.c @@ -266,14 +266,17 @@ 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, @@ -287,14 +290,20 @@ 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; -- 2.2.2