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perf tools: Add dso__data_* interface descriptons

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Adding descriptions/explanations for dso__data_* interface
functions.

Acked-by: Namhyung Kim <namhyung@kernel.org>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jean Pihet <jean.pihet@linaro.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1401892622-30848-10-git-send-email-jolsa@kernel.org
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
This commit is contained in:
Jiri Olsa 2014-05-07 21:09:59 +02:00
parent a08cae03f4
commit c1f9aa0a61
2 changed files with 97 additions and 0 deletions
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59
tools/perf/util/dso.c
View File

@ -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)

38
tools/perf/util/dso.h
View File

@ -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);