diff options
author | Ian Rogers <irogers@google.com> | 2020-05-01 15:13:14 -0700 |
---|---|---|
committer | Arnaldo Carvalho de Melo <acme@redhat.com> | 2020-05-05 16:35:32 -0300 |
commit | 53df2b93441289848f5c2e76d19d1569816b2b9d (patch) | |
tree | 8f296be512c7ba66675fd8762656b67d498b2939 | |
parent | 51876bd45263f62083bbb823220bfb48909f313a (diff) | |
download | linux-53df2b93441289848f5c2e76d19d1569816b2b9d.tar.bz2 |
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@google.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lore.kernel.org/lkml/20200501221315.54715-3-irogers@google.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
-rw-r--r-- | tools/lib/api/io.h | 3 | ||||
-rw-r--r-- | 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; } |