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Date: Wed, 6 May 2020 12:22:31 -0300
From: Arnaldo Carvalho de Melo <acme@...nel.org>
To: Ingo Molnar <mingo@...nel.org>,
Thomas Gleixner <tglx@...utronix.de>
Cc: Jiri Olsa <jolsa@...nel.org>, Namhyung Kim <namhyung@...nel.org>,
Clark Williams <williams@...hat.com>,
linux-kernel@...r.kernel.org, linux-perf-users@...r.kernel.org,
Ian Rogers <irogers@...gle.com>,
Arnaldo Carvalho de Melo <acme@...hat.com>,
Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
Jiri Olsa <jolsa@...hat.com>,
Mark Rutland <mark.rutland@....com>,
Peter Zijlstra <peterz@...radead.org>,
Stephane Eranian <eranian@...gle.com>
Subject: [PATCH 88/91] libsymbols kallsyms: Parse using io api
From: Ian Rogers <irogers@...gle.com>
'perf record' will call kallsyms__parse 4 times during startup and
process megabytes of data. This changes kallsyms__parse to use the io
library rather than fgets to improve performance of the user code by
over 8%.
Before:
Running 'internals/kallsyms-parse' benchmark:
Average kallsyms__parse took: 103.988 ms (+- 0.203 ms)
After:
Running 'internals/kallsyms-parse' benchmark:
Average kallsyms__parse took: 95.571 ms (+- 0.006 ms)
For a workload like:
$ perf record /bin/true
Run under 'perf record -e cycles:u -g' the time goes from:
Before
30.10% 1.67% perf perf [.] kallsyms__parse
After
25.55% 20.04% perf perf [.] kallsyms__parse
So a little under 5% of the start-up time is removed. A lot of what
remains is on the kernel side, but caching kallsyms within perf would at
least impact memory footprint.
Committer notes:
The internal/kallsyms-parse bench is run using:
[root@...e ~]# perf bench internals kallsyms-parse
# Running 'internals/kallsyms-parse' benchmark:
Average kallsyms__parse took: 80.381 ms (+- 0.115 ms)
[root@...e ~]#
And this pre-existing test uses these routines to parse kallsyms and
then compare with the info obtained from the matching ELF symtab:
[root@...e ~]# perf test vmlinux
1: vmlinux symtab matches kallsyms : Ok
[root@...e ~]#
Also we can't remove hex2u64() in this patch as this breaks the build:
/usr/bin/ld: /tmp/build/perf/perf-in.o: in function `modules__parse':
/home/acme/git/perf/tools/perf/util/symbol.c:607: undefined reference to `hex2u64'
/usr/bin/ld: /home/acme/git/perf/tools/perf/util/symbol.c:607: undefined reference to `hex2u64'
/usr/bin/ld: /tmp/build/perf/perf-in.o: in function `dso__load_perf_map':
/home/acme/git/perf/tools/perf/util/symbol.c:1477: undefined reference to `hex2u64'
/usr/bin/ld: /home/acme/git/perf/tools/perf/util/symbol.c:1483: undefined reference to `hex2u64'
collect2: error: ld returned 1 exit status
Leave it there, move it in the next patch.
Signed-off-by: Ian Rogers <irogers@...gle.com>
Tested-by: Arnaldo Carvalho de Melo <acme@...hat.com>
Cc: Alexander Shishkin <alexander.shishkin@...ux.intel.com>
Cc: Jiri Olsa <jolsa@...hat.com>
Cc: Mark Rutland <mark.rutland@....com>
Cc: Namhyung Kim <namhyung@...nel.org>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Stephane Eranian <eranian@...gle.com>
Cc: Thomas Gleixner <tglx@...utronix.de>
Link: http://lore.kernel.org/lkml/20200501221315.54715-3-irogers@google.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@...hat.com>
---
tools/lib/api/io.h | 3 ++
tools/lib/symbol/kallsyms.c | 93 +++++++++++++++++++------------------
2 files changed, 51 insertions(+), 45 deletions(-)
diff --git a/tools/lib/api/io.h b/tools/lib/api/io.h
index b7e55b5f8a4a..777c20f6b604 100644
--- a/tools/lib/api/io.h
+++ b/tools/lib/api/io.h
@@ -7,6 +7,9 @@
#ifndef __API_IO__
#define __API_IO__
+#include <stdlib.h>
+#include <unistd.h>
+
struct io {
/* File descriptor being read/ */
int fd;
diff --git a/tools/lib/symbol/kallsyms.c b/tools/lib/symbol/kallsyms.c
index 1a7a9f877095..a5edc75c346c 100644
--- a/tools/lib/symbol/kallsyms.c
+++ b/tools/lib/symbol/kallsyms.c
@@ -1,7 +1,9 @@
// SPDX-License-Identifier: GPL-2.0
#include "symbol/kallsyms.h"
+#include "api/io.h"
#include <stdio.h>
-#include <stdlib.h>
+#include <sys/stat.h>
+#include <fcntl.h>
u8 kallsyms2elf_type(char type)
{
@@ -9,12 +11,6 @@ u8 kallsyms2elf_type(char type)
return (type == 't' || type == 'w') ? STT_FUNC : STT_OBJECT;
}
-bool kallsyms__is_function(char symbol_type)
-{
- symbol_type = toupper(symbol_type);
- return symbol_type == 'T' || symbol_type == 'W';
-}
-
/*
* While we find nice hex chars, build a long_val.
* Return number of chars processed.
@@ -28,61 +24,68 @@ int hex2u64(const char *ptr, u64 *long_val)
return p - ptr;
}
+bool kallsyms__is_function(char symbol_type)
+{
+ symbol_type = toupper(symbol_type);
+ return symbol_type == 'T' || symbol_type == 'W';
+}
+
+static void read_to_eol(struct io *io)
+{
+ int ch;
+
+ for (;;) {
+ ch = io__get_char(io);
+ if (ch < 0 || ch == '\n')
+ return;
+ }
+}
+
int kallsyms__parse(const char *filename, void *arg,
int (*process_symbol)(void *arg, const char *name,
char type, u64 start))
{
- char *line = NULL;
- size_t n;
- int err = -1;
- FILE *file = fopen(filename, "r");
-
- if (file == NULL)
- goto out_failure;
-
- err = 0;
+ struct io io;
+ char bf[BUFSIZ];
+ int err;
- while (!feof(file)) {
- u64 start;
- int line_len, len;
- char symbol_type;
- char *symbol_name;
+ io.fd = open(filename, O_RDONLY, 0);
- line_len = getline(&line, &n, file);
- if (line_len < 0 || !line)
- break;
+ if (io.fd < 0)
+ return -1;
- line[--line_len] = '\0'; /* \n */
+ io__init(&io, io.fd, bf, sizeof(bf));
- len = hex2u64(line, &start);
+ err = 0;
+ while (!io.eof) {
+ __u64 start;
+ int ch;
+ size_t i;
+ char symbol_type;
+ char symbol_name[KSYM_NAME_LEN + 1];
- /* Skip the line if we failed to parse the address. */
- if (!len)
+ if (io__get_hex(&io, &start) != ' ') {
+ read_to_eol(&io);
continue;
-
- len++;
- if (len + 2 >= line_len)
+ }
+ symbol_type = io__get_char(&io);
+ if (io__get_char(&io) != ' ') {
+ read_to_eol(&io);
continue;
-
- symbol_type = line[len];
- len += 2;
- symbol_name = line + len;
- len = line_len - len;
-
- if (len >= KSYM_NAME_LEN) {
- err = -1;
- break;
}
+ for (i = 0; i < sizeof(symbol_name); i++) {
+ ch = io__get_char(&io);
+ if (ch < 0 || ch == '\n')
+ break;
+ symbol_name[i] = ch;
+ }
+ symbol_name[i] = '\0';
err = process_symbol(arg, symbol_name, symbol_type, start);
if (err)
break;
}
- free(line);
- fclose(file);
+ close(io.fd);
return err;
-
-out_failure:
- return -1;
}
--
2.21.1
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