The following commit has been merged into the perf/core branch of tip:
Commit-ID: 53df2b93441289848f5c2e76d19d1569816b2b9d
Gitweb: https://git.kernel.org/tip/53df2b93441289848f5c2e76d19d1569816b2b9d
Author: Ian Rogers <irogers@xxxxxxxxxx>
AuthorDate: Fri, 01 May 2020 15:13:14 -07:00
Committer: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
CommitterDate: Tue, 05 May 2020 16:35:32 -03:00
libsymbols kallsyms: Parse using io api
'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@five ~]# perf bench internals kallsyms-parse
# Running 'internals/kallsyms-parse' benchmark:
Average kallsyms__parse took: 80.381 ms (+- 0.115 ms)
[root@five ~]#
And this pre-existing test uses these routines to parse kallsyms and
then compare with the info obtained from the matching ELF symtab:
[root@five ~]# perf test vmlinux
1: vmlinux symtab matches kallsyms : Ok
[root@five ~]#
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@xxxxxxxxxx>
Tested-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
Cc: Alexander Shishkin <alexander.shishkin@xxxxxxxxxxxxxxx>
Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
Cc: Mark Rutland <mark.rutland@xxxxxxx>
Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Stephane Eranian <eranian@xxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Link: http://lore.kernel.org/lkml/20200501221315.54715-3-irogers@xxxxxxxxxx
Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
---
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 b7e55b5..777c20f 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 1a7a9f8..a5edc75 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;
}
|