From 53df2b93441289848f5c2e76d19d1569816b2b9d Mon Sep 17 00:00:00 2001 From: Ian Rogers Date: Fri, 1 May 2020 15:13:14 -0700 Subject: [PATCH] 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 Tested-by: Arnaldo Carvalho de Melo Cc: Alexander Shishkin Cc: Jiri Olsa Cc: Mark Rutland Cc: Namhyung Kim Cc: Peter Zijlstra Cc: Stephane Eranian Cc: Thomas Gleixner Link: http://lore.kernel.org/lkml/20200501221315.54715-3-irogers@google.com Signed-off-by: Arnaldo Carvalho de Melo --- tools/lib/api/io.h | 3 ++ tools/lib/symbol/kallsyms.c | 95 +++++++++++++++++++------------------ 2 files changed, 52 insertions(+), 46 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 +#include + 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 -#include +#include +#include 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"); + struct io io; + char bf[BUFSIZ]; + int err; - if (file == NULL) - goto out_failure; + io.fd = open(filename, O_RDONLY, 0); + + if (io.fd < 0) + return -1; + + io__init(&io, io.fd, bf, sizeof(bf)); err = 0; - - while (!feof(file)) { - u64 start; - int line_len, len; + while (!io.eof) { + __u64 start; + int ch; + size_t i; char symbol_type; - char *symbol_name; + char symbol_name[KSYM_NAME_LEN + 1]; - line_len = getline(&line, &n, file); - if (line_len < 0 || !line) - break; - - line[--line_len] = '\0'; /* \n */ - - len = hex2u64(line, &start); - - /* 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) - continue; - - symbol_type = line[len]; - len += 2; - symbol_name = line + len; - len = line_len - len; - - if (len >= KSYM_NAME_LEN) { - err = -1; - break; } + symbol_type = io__get_char(&io); + if (io__get_char(&io) != ' ') { + read_to_eol(&io); + continue; + } + 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; }