From: Masami Hiramatsu <mhiramat@kernel.org>
To: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Jiri Olsa <jolsa@redhat.com>, Namhyung Kim <namhyung@kernel.org>,
Masami Hiramatsu <mhiramat@kernel.org>,
linux-kernel@vger.kernel.org
Subject: [BUGFIX PATCH 1/4] perf probe: Skip end-of-sequence and non statement lines
Date: Wed, 30 Oct 2019 16:09:21 +0900 [thread overview]
Message-ID: <157241936090.32002.12156347518596111660.stgit@devnote2> (raw)
In-Reply-To: <157241935028.32002.10228194508152968737.stgit@devnote2>
Skip end-of-sequence and non-statement lines while walking
through lines list.
The "end-of-sequence" line information means
"the current address is that of the first byte after the
end of a sequence of target machine instructions."
(DWARF version 4 spec 6.2.2)
This actually means out of scope and we can not probe on it.
On the other hand, the statement lines (is_stmt) means
"the current instruction is a recommended breakpoint location.
A recommended breakpoint location is intended to “represent”
a line, a statement and/or a semantically distinct subpart
of a statement."
(DWARF version 4 spec 6.2.2)
So, non-statement line info also should be skipped.
These can reduce unneeded probe points and also avoid an error.
E.g. without this patch,
# perf probe -a "clear_tasks_mm_cpumask:1"
Added new events:
probe:clear_tasks_mm_cpumask (on clear_tasks_mm_cpumask:1)
probe:clear_tasks_mm_cpumask_1 (on clear_tasks_mm_cpumask:1)
probe:clear_tasks_mm_cpumask_2 (on clear_tasks_mm_cpumask:1)
probe:clear_tasks_mm_cpumask_3 (on clear_tasks_mm_cpumask:1)
probe:clear_tasks_mm_cpumask_4 (on clear_tasks_mm_cpumask:1)
You can now use it in all perf tools, such as:
perf record -e probe:clear_tasks_mm_cpumask_4 -aR sleep 1
#
This puts 5 probes on one line, but acutally it's not inlined
function. This is because there are many non statement instructions
at the function prologue.
With this patch,
# perf probe -a "clear_tasks_mm_cpumask:1"
Added new event:
probe:clear_tasks_mm_cpumask (on clear_tasks_mm_cpumask:1)
You can now use it in all perf tools, such as:
perf record -e probe:clear_tasks_mm_cpumask -aR sleep 1
#
Now perf-probe skips unneeded addresses.
Fixes: 4cc9cec636e7 ("perf probe: Introduce lines walker interface")
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
---
tools/perf/util/dwarf-aux.c | 7 +++++++
1 file changed, 7 insertions(+)
diff --git a/tools/perf/util/dwarf-aux.c b/tools/perf/util/dwarf-aux.c
index ac82fd937e4b..f31001d13bfb 100644
--- a/tools/perf/util/dwarf-aux.c
+++ b/tools/perf/util/dwarf-aux.c
@@ -782,6 +782,7 @@ int die_walk_lines(Dwarf_Die *rt_die, line_walk_callback_t callback, void *data)
int decl = 0, inl;
Dwarf_Die die_mem, *cu_die;
size_t nlines, i;
+ bool flag;
/* Get the CU die */
if (dwarf_tag(rt_die) != DW_TAG_compile_unit) {
@@ -812,6 +813,12 @@ int die_walk_lines(Dwarf_Die *rt_die, line_walk_callback_t callback, void *data)
"Possible error in debuginfo.\n");
continue;
}
+ /* Skip end-of-sequence */
+ if (dwarf_lineendsequence(line, &flag) != 0 || flag)
+ continue;
+ /* Skip Non statement line-info */
+ if (dwarf_linebeginstatement(line, &flag) != 0 || !flag)
+ continue;
/* Filter lines based on address */
if (rt_die != cu_die) {
/*
next prev parent reply other threads:[~2019-10-30 7:09 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-30 7:09 [BUGFIX PATCH 0/4] perf probe: Fixes bugs in show-lines and show vars etc Masami Hiramatsu
2019-10-30 7:09 ` Masami Hiramatsu [this message]
2019-11-06 20:04 ` [BUGFIX PATCH 1/4] perf probe: Skip end-of-sequence and non statement lines Arnaldo Carvalho de Melo
2020-01-10 9:29 ` Rantala, Tommi T. (Nokia - FI/Espoo)
2020-01-10 15:43 ` Masami Hiramatsu
2019-11-12 11:17 ` [tip: perf/core] " tip-bot2 for Masami Hiramatsu
2019-10-30 7:09 ` [BUGFIX PATCH 2/4] perf probe: Filter out instances except for inlined subroutine and subprogram Masami Hiramatsu
2019-11-06 20:06 ` Arnaldo Carvalho de Melo
2019-11-12 11:17 ` [tip: perf/core] " tip-bot2 for Masami Hiramatsu
2019-10-30 7:09 ` [BUGFIX PATCH 3/4] perf probe: Fix to show calling lines of inlined functions Masami Hiramatsu
2019-11-06 20:08 ` Arnaldo Carvalho de Melo
2019-11-12 11:17 ` [tip: perf/core] " tip-bot2 for Masami Hiramatsu
2019-10-30 7:09 ` [BUGFIX PATCH 4/4] perf probe: Skip overlapped location on searching variables Masami Hiramatsu
2019-11-06 20:09 ` Arnaldo Carvalho de Melo
2019-11-12 11:17 ` [tip: perf/core] " tip-bot2 for Masami Hiramatsu
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=157241936090.32002.12156347518596111660.stgit@devnote2 \
--to=mhiramat@kernel.org \
--cc=acme@kernel.org \
--cc=jolsa@redhat.com \
--cc=linux-kernel@vger.kernel.org \
--cc=namhyung@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).