From: Arnaldo Carvalho de Melo <acme@kernel.org>
To: Ingo Molnar <mingo@kernel.org>
Cc: linux-kernel@vger.kernel.org, Anton Blanchard <anton@samba.org>,
Ingo Molnar <mingo@redhat.com>, Paul Mackerras <paulus@samba.org>,
Peter Zijlstra <a.p.zijlstra@chello.nl>,
Arnaldo Carvalho de Melo <acme@redhat.com>
Subject: [PATCH 16/20] perf symbols: Ignore stripped vmlinux and fallback to kallsyms
Date: Wed, 17 Sep 2014 18:24:19 -0300 [thread overview]
Message-ID: <1410989063-14207-17-git-send-email-acme@kernel.org> (raw)
In-Reply-To: <1410989063-14207-1-git-send-email-acme@kernel.org>
From: Anton Blanchard <anton@samba.org>
If a vmlinux is stripped, perf will use it and ignore kallsyms. We
end up with useless profiles where everything maps to a few
runtime symbols:
63.39% swapper [kernel.kallsyms] [k] hcall_real_table
4.90% beam.smp [kernel.kallsyms] [k] hcall_real_table
4.44% beam.smp [kernel.kallsyms] [k] __sched_text_start
3.72% beam.smp [kernel.kallsyms] [k] __run_at_kexec
Detect this case and fallback to using kallsyms. This fixes the issue:
62.81% swapper [kernel.kallsyms] [k] snooze_loop
4.44% beam.smp [kernel.kallsyms] [k] __schedule
0.91% beam.smp [kernel.kallsyms] [k] _switch
0.73% beam.smp [kernel.kallsyms] [k] put_prev_entity
Signed-off-by: Anton Blanchard <anton@samba.org>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/20140909085929.4a5a81f0@kryten
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
tools/perf/util/symbol-elf.c | 8 ++++++++
1 file changed, 8 insertions(+)
diff --git a/tools/perf/util/symbol-elf.c b/tools/perf/util/symbol-elf.c
index 9c9b27fbc78d..2a92e10317c5 100644
--- a/tools/perf/util/symbol-elf.c
+++ b/tools/perf/util/symbol-elf.c
@@ -717,6 +717,14 @@ int dso__load_sym(struct dso *dso, struct map *map,
symbols__delete(&dso->symbols[map->type]);
if (!syms_ss->symtab) {
+ /*
+ * If the vmlinux is stripped, fail so we will fall back
+ * to using kallsyms. The vmlinux runtime symbols aren't
+ * of much use.
+ */
+ if (dso->kernel)
+ goto out_elf_end;
+
syms_ss->symtab = syms_ss->dynsym;
syms_ss->symshdr = syms_ss->dynshdr;
}
--
1.9.3
next prev parent reply other threads:[~2014-09-17 21:25 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-09-17 21:24 [GIT PULL 00/20] perf/core improvements and fixes Arnaldo Carvalho de Melo
2014-09-17 21:24 ` [PATCH 01/20] perf tools: Add +field argument support for --sort option Arnaldo Carvalho de Melo
2014-09-17 21:24 ` [PATCH 02/20] perf tools powerpc: Fix build issue when DWARF support is disabled Arnaldo Carvalho de Melo
2014-09-17 21:24 ` [PATCH 03/20] perf kvm stat report: Save pid string in opts.target.pid Arnaldo Carvalho de Melo
2014-09-17 21:24 ` [PATCH 04/20] perf kvm stat report: Enable the target.system_wide flag Arnaldo Carvalho de Melo
2014-09-17 21:24 ` [PATCH 05/20] perf kvm stat report: Unify the title bar output Arnaldo Carvalho de Melo
2014-09-17 21:24 ` [PATCH 06/20] perf tools: Allow to specify lib compile variable for spec usage Arnaldo Carvalho de Melo
2014-09-17 21:24 ` [PATCH 07/20] perf tools: Let a user specify a PMU event without any config terms Arnaldo Carvalho de Melo
2014-09-17 21:24 ` [PATCH 08/20] perf tools: Add perf-with-kcore script Arnaldo Carvalho de Melo
2014-09-17 21:24 ` [PATCH 09/20] perf tools: Let default config be defined for a PMU Arnaldo Carvalho de Melo
2014-09-17 21:24 ` [PATCH 10/20] perf tools: Add perf_pmu__scan_file() Arnaldo Carvalho de Melo
2014-09-17 21:24 ` [PATCH 11/20] perf tool: fix compilation for ARM Arnaldo Carvalho de Melo
2014-09-17 21:24 ` [PATCH 12/20] perf tools: Disable kernel symbol demangling by default Arnaldo Carvalho de Melo
2014-09-17 21:24 ` [PATCH 13/20] perf tools: Fix GNU-only grep usage in Makefile Arnaldo Carvalho de Melo
2014-09-17 21:24 ` [PATCH 14/20] perf tools: Don't include sys/poll.h directly Arnaldo Carvalho de Melo
2014-09-17 21:24 ` [PATCH 15/20] perf tools: define _DEFAULT_SOURCE for glibc_2.20 Arnaldo Carvalho de Melo
2014-09-17 21:24 ` Arnaldo Carvalho de Melo [this message]
2014-09-17 21:24 ` [PATCH 17/20] perf symbols: Add path to Ubuntu kernel debuginfo file Arnaldo Carvalho de Melo
2014-09-17 21:24 ` [PATCH 18/20] perf probe: Do not access kallsyms when analyzing user binaries Arnaldo Carvalho de Melo
2014-09-17 21:24 ` [PATCH 19/20] perf probe: Do not use dwfl_module_addrsym if dwarf_diename finds symbol name Arnaldo Carvalho de Melo
2014-09-17 21:24 ` [PATCH 20/20] perf record: Use ring buffer consume method to look like other tools Arnaldo Carvalho de Melo
2014-09-19 5:15 ` [GIT PULL 00/20] perf/core improvements and fixes Ingo Molnar
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