From: Jiri Olsa Date: Wed, 7 May 2014 19:09:59 +0000 (+0200) Subject: perf tools: Add dso__data_* interface descriptons X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=c1f9aa0a61bde512a68060883d1c3c1955a546ea;p=GitHub%2Fmoto-9609%2Fandroid_kernel_motorola_exynos9610.git perf tools: Add dso__data_* interface descriptons Adding descriptions/explanations for dso__data_* interface functions. Acked-by: Namhyung Kim Cc: Arnaldo Carvalho de Melo Cc: Corey Ashford Cc: David Ahern Cc: Frederic Weisbecker Cc: Ingo Molnar Cc: Jean Pihet Cc: Namhyung Kim Cc: Paul Mackerras Cc: Peter Zijlstra Link: http://lkml.kernel.org/r/1401892622-30848-10-git-send-email-jolsa@kernel.org Signed-off-by: Jiri Olsa --- diff --git a/tools/perf/util/dso.c b/tools/perf/util/dso.c index c30752c7eebb..819f10414f08 100644 --- a/tools/perf/util/dso.c +++ b/tools/perf/util/dso.c @@ -205,6 +205,13 @@ static int __open_dso(struct dso *dso, struct machine *machine) static void check_data_close(void); +/** + * dso_close - Open DSO data file + * @dso: dso object + * + * Open @dso's data file descriptor and updates + * list/count of open DSO objects. + */ static int open_dso(struct dso *dso, struct machine *machine) { int fd = __open_dso(dso, machine); @@ -231,6 +238,13 @@ static void close_data_fd(struct dso *dso) } } +/** + * dso_close - Close DSO data file + * @dso: dso object + * + * Close @dso's data file descriptor and updates + * list/count of open DSO objects. + */ static void close_dso(struct dso *dso) { close_data_fd(dso); @@ -276,6 +290,11 @@ static bool may_cache_fd(void) return limit > (rlim_t) dso__data_open_cnt; } +/* + * Check and close LRU dso if we crossed allowed limit + * for opened dso file descriptors. The limit is half + * of the RLIMIT_NOFILE files opened. +*/ static void check_data_close(void) { bool cache_fd = may_cache_fd(); @@ -284,11 +303,25 @@ static void check_data_close(void) close_first_dso(); } +/** + * dso__data_close - Close DSO data file + * @dso: dso object + * + * External interface to close @dso's data file descriptor. + */ void dso__data_close(struct dso *dso) { close_dso(dso); } +/** + * dso__data_fd - Get dso's data file descriptor + * @dso: dso object + * @machine: machine object + * + * External interface to find dso's file, open it and + * returns file descriptor. + */ int dso__data_fd(struct dso *dso, struct machine *machine) { enum dso_binary_type binary_type_data[] = { @@ -445,6 +478,11 @@ static ssize_t dso_cache_read(struct dso *dso, u64 offset, return dso_cache__read(dso, offset, data, size); } +/* + * Reads and caches dso data DSO__DATA_CACHE_SIZE size chunks + * in the rb_tree. Any read to already cached data is served + * by cached data. + */ static ssize_t cached_read(struct dso *dso, u64 offset, u8 *data, ssize_t size) { ssize_t r = 0; @@ -504,6 +542,17 @@ static ssize_t data_read_offset(struct dso *dso, u64 offset, return cached_read(dso, offset, data, size); } +/** + * dso__data_read_offset - Read data from dso file offset + * @dso: dso object + * @machine: machine object + * @offset: file offset + * @data: buffer to store data + * @size: size of the @data buffer + * + * External interface to read data from dso file offset. Open + * dso data file and use cached_read to get the data. + */ ssize_t dso__data_read_offset(struct dso *dso, struct machine *machine, u64 offset, u8 *data, ssize_t size) { @@ -513,6 +562,16 @@ ssize_t dso__data_read_offset(struct dso *dso, struct machine *machine, return data_read_offset(dso, offset, data, size); } +/** + * dso__data_read_addr - Read data from dso address + * @dso: dso object + * @machine: machine object + * @add: virtual memory address + * @data: buffer to store data + * @size: size of the @data buffer + * + * External interface to read data from dso address. + */ ssize_t dso__data_read_addr(struct dso *dso, struct map *map, struct machine *machine, u64 addr, u8 *data, ssize_t size) diff --git a/tools/perf/util/dso.h b/tools/perf/util/dso.h index da47b13595f3..ad553ba257bf 100644 --- a/tools/perf/util/dso.h +++ b/tools/perf/util/dso.h @@ -149,6 +149,44 @@ char dso__symtab_origin(const struct dso *dso); int dso__read_binary_type_filename(const struct dso *dso, enum dso_binary_type type, char *root_dir, char *filename, size_t size); +/* + * The dso__data_* external interface provides following functions: + * dso__data_fd + * dso__data_close + * dso__data_read_offset + * dso__data_read_addr + * + * Please refer to the dso.c object code for each function and + * arguments documentation. Following text tries to explain the + * dso file descriptor caching. + * + * The dso__data* interface allows caching of opened file descriptors + * to speed up the dso data accesses. The idea is to leave the file + * descriptor opened ideally for the whole life of the dso object. + * + * The current usage of the dso__data_* interface is as follows: + * + * Get DSO's fd: + * int fd = dso__data_fd(dso, machine); + * USE 'fd' SOMEHOW + * + * Read DSO's data: + * n = dso__data_read_offset(dso_0, &machine, 0, buf, BUFSIZE); + * n = dso__data_read_addr(dso_0, &machine, 0, buf, BUFSIZE); + * + * Eventually close DSO's fd: + * dso__data_close(dso); + * + * It is not necessary to close the DSO object data file. Each time new + * DSO data file is opened, the limit (RLIMIT_NOFILE/2) is checked. Once + * it is crossed, the oldest opened DSO object is closed. + * + * The dso__delete function calls close_dso function to ensure the + * data file descriptor gets closed/unmapped before the dso object + * is freed. + * + * TODO +*/ int dso__data_fd(struct dso *dso, struct machine *machine); void dso__data_close(struct dso *dso);