From b6a15269cee255dc5fe75c249c701e3956d892cb Mon Sep 17 00:00:00 2001 From: Ian Rogers Date: Mon, 27 Nov 2023 14:08:16 -0800 Subject: tools api fs: Switch filename__read_str to use io.h filename__read_str() has its own string reading code that allocates memory before reading into it. The memory allocated is sized at BUFSIZ that is 8kb. Most strings are short and so most of this 8kb is wasted. Refactor io__getline(), as io__getdelim(), so that the newline character can be configurable and ignored in the case of filename__read_str(). Code like build_caches_for_cpu() in perf's header.c will read many strings and hold them in a data structure, in this case multiple strings per cache level per CPU. Using io.h's io__getline() avoids the wasted memory as strings are temporarily read into a buffer on the stack before being copied to a buffer that grows 128 bytes at a time and is never sized larger than the string. For a 16 hyperthread system the memory consumption of "perf record true" is reduced by 180kb, primarily through saving memory when reading the cache information. Signed-off-by: Ian Rogers Acked-by: Namhyung Kim Cc: Adrian Hunter Cc: Alexander Shishkin Cc: Andi Kleen Cc: Athira Jajeev Cc: Changbin Du Cc: Colin Ian King Cc: Dmitrii Dolgov <9erthalion6@gmail.com> Cc: German Gomez Cc: Guilherme Amadio Cc: Huacai Chen Cc: Ingo Molnar Cc: James Clark Cc: Jiri Olsa Cc: K Prateek Nayak Cc: Kajol Jain Cc: Kan Liang Cc: Leo Yan Cc: Li Dong Cc: Liam Howlett Cc: Mark Rutland Cc: Masami Hiramatsu (Google) Cc: Miguel Ojeda Cc: Ming Wang Cc: Nick Terrell Cc: Paolo Bonzini Cc: Peter Zijlstra Cc: Ravi Bangoria Cc: Sandipan Das Cc: Sean Christopherson Cc: Steinar H. Gunderson Cc: Vincent Whitchurch Cc: Wenyu Liu Cc: Yang Jihong Link: https://lore.kernel.org/r/20231127220902.1315692-5-irogers@google.com Signed-off-by: Arnaldo Carvalho de Melo --- tools/lib/api/fs/fs.c | 56 +++++++++++++-------------------------------------- tools/lib/api/io.h | 11 +++++++--- 2 files changed, 22 insertions(+), 45 deletions(-) (limited to 'tools/lib/api') diff --git a/tools/lib/api/fs/fs.c b/tools/lib/api/fs/fs.c index 5cb0eeec2c8a..004f2af5504b 100644 --- a/tools/lib/api/fs/fs.c +++ b/tools/lib/api/fs/fs.c @@ -16,6 +16,7 @@ #include #include "fs.h" +#include "../io.h" #include "debug-internal.h" #define _STR(x) #x @@ -344,53 +345,24 @@ int filename__read_ull(const char *filename, unsigned long long *value) return filename__read_ull_base(filename, value, 0); } -#define STRERR_BUFSIZE 128 /* For the buffer size of strerror_r */ - int filename__read_str(const char *filename, char **buf, size_t *sizep) { - size_t size = 0, alloc_size = 0; - void *bf = NULL, *nbf; - int fd, n, err = 0; - char sbuf[STRERR_BUFSIZE]; + struct io io; + char bf[128]; + int err; - fd = open(filename, O_RDONLY); - if (fd < 0) + io.fd = open(filename, O_RDONLY); + if (io.fd < 0) return -errno; - - do { - if (size == alloc_size) { - alloc_size += BUFSIZ; - nbf = realloc(bf, alloc_size); - if (!nbf) { - err = -ENOMEM; - break; - } - - bf = nbf; - } - - n = read(fd, bf + size, alloc_size - size); - if (n < 0) { - if (size) { - pr_warn("read failed %d: %s\n", errno, - strerror_r(errno, sbuf, sizeof(sbuf))); - err = 0; - } else - err = -errno; - - break; - } - - size += n; - } while (n > 0); - - if (!err) { - *sizep = size; - *buf = bf; + io__init(&io, io.fd, bf, sizeof(bf)); + *buf = NULL; + err = io__getdelim(&io, buf, sizep, /*delim=*/-1); + if (err < 0) { + free(*buf); + *buf = NULL; } else - free(bf); - - close(fd); + err = 0; + close(io.fd); return err; } diff --git a/tools/lib/api/io.h b/tools/lib/api/io.h index 2a7fe9758813..84adf8102018 100644 --- a/tools/lib/api/io.h +++ b/tools/lib/api/io.h @@ -141,8 +141,8 @@ static inline int io__get_dec(struct io *io, __u64 *dec) } } -/* Read up to and including the first newline following the pattern of getline. */ -static inline ssize_t io__getline(struct io *io, char **line_out, size_t *line_len_out) +/* Read up to and including the first delim. */ +static inline ssize_t io__getdelim(struct io *io, char **line_out, size_t *line_len_out, int delim) { char buf[128]; int buf_pos = 0; @@ -152,7 +152,7 @@ static inline ssize_t io__getline(struct io *io, char **line_out, size_t *line_l /* TODO: reuse previously allocated memory. */ free(*line_out); - while (ch != '\n') { + while (ch != delim) { ch = io__get_char(io); if (ch < 0) @@ -185,4 +185,9 @@ err_out: return -ENOMEM; } +static inline ssize_t io__getline(struct io *io, char **line_out, size_t *line_len_out) +{ + return io__getdelim(io, line_out, line_len_out, /*delim=*/'\n'); +} + #endif /* __API_IO__ */ -- cgit v1.2.3-59-g8ed1b