lkml.org 
[lkml]   [2010]   [Mar]   [3]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
Subject[RFC] [PATCH 1/1] perf: add support for arch-dependent symbolic event names to "perf stat"
For your review, this patch adds support for arch-dependent symbolic event names 
to the "perf stat" tool, and could be expanded to other "perf *" commands fairly
easily, I suspect.

To support arch-dependent event names without adding arch-dependent code to
perf, I added a callout mechanism whereby perf will look for the environment
variable: PERF_ARCH_DEP_LIB, and if it exists, it will try to open it as a
shared object. If that succeeds, it looks for the symbol
"parse_arch_dep_event". If that exists, that function will be called by
parse_events() before all of the other event parsing functions in
parse-events.c. It is passed the same arguments as the other parse_*_event
functions, namely the event string and a pointer to an event attribute structure.

As the code existed, "perf stat" would print out the count results, but for raw
events (which is how arch-dependent events are supported in perf_events), it
would just print out a raw code. This is not acceptable, especially when a
symbolic name was placed on the command line. So I changed the code to save
away the event name that was passed on the command line, rather than doing a
reverse translation to an event string based on the event type and config fields
of the attr structure. In this way, there's no need for a reverse translation
function in the arch-dependent library; only a event string->attr struct
function is needed.

I could well be missing something, but I don't understand why reverse
translation is ever needed in perf, as long as the tool keeps track of the
original event strings.

Thanks for your consideration,

- Corey

Corey Ashford
Software Engineer
IBM Linux Technology Center, Linux Toolchain
Beaverton, OR
503-578-3507
cjashfor@us.ibm.com

diff --git a/tools/perf/Makefile b/tools/perf/Makefile
index 54a5b50..20d3255 100644
--- a/tools/perf/Makefile
+++ b/tools/perf/Makefile
@@ -199,7 +199,7 @@ ifndef PERF_DEBUG
endif

CFLAGS = -ggdb3 -Wall -Wextra -std=gnu99 -Werror $(CFLAGS_OPTIMIZE) -D_FORTIFY_SOURCE=2 $(EXTRA_WARNINGS) $(EXTRA_CFLAGS)
-EXTLIBS = -lpthread -lrt -lelf -lm
+EXTLIBS = -lpthread -lrt -lelf -lm -ldl
ALL_CFLAGS = $(CFLAGS)
ALL_LDFLAGS = $(LDFLAGS)
STRIP ?= strip
diff --git a/tools/perf/util/parse-events.c b/tools/perf/util/parse-events.c
index 05d0c5c..ba4a663 100644
--- a/tools/perf/util/parse-events.c
+++ b/tools/perf/util/parse-events.c
@@ -8,11 +8,13 @@
#include "cache.h"
#include "header.h"
#include "debugfs.h"
+#include "dlfcn.h"

int nr_counters;

struct perf_event_attr attrs[MAX_COUNTERS];
char *filters[MAX_COUNTERS];
+char *event_names[MAX_COUNTERS];

struct event_symbol {
u8 type;
@@ -267,10 +269,7 @@ static char *event_cache_name(u8 cache_type, u8 cache_op, u8 cache_result)

const char *event_name(int counter)
{
- u64 config = attrs[counter].config;
- int type = attrs[counter].type;
-
- return __event_name(type, config);
+ return event_names[counter];
}

const char *__event_name(int type, u64 config)
@@ -324,6 +323,38 @@ const char *__event_name(int type, u64 config)
return "unknown";
}

+#define PERF_ARCH_DEP_LIB_ENV_VAR "PERF_ARCH_DEP_LIB"
+
+static int arch_dep_lib_initialized = 0;
+static int (*parse_arch_dep_event_callout)(const char **strp,
+ struct perf_event_attr *attr) = NULL;
+
+static void initialize_arch_dep_lib(void)
+{
+ char *lib_name = getenv(PERF_ARCH_DEP_LIB_ENV_VAR);
+ void *lib_handle;
+
+ if (!lib_name)
+ return;
+
+ lib_handle = dlopen(lib_name, RTLD_NOW);
+ if (!lib_handle) {
+ fprintf(stderr, "The environment variable %s is set to %s, "
+ "but we couldn't open it. error: %s\n",
+ PERF_ARCH_DEP_LIB_ENV_VAR, lib_name, dlerror());
+ exit(1);
+ }
+ parse_arch_dep_event_callout = dlsym(lib_handle, "parse_arch_dep_event");
+ if (!parse_arch_dep_event_callout) {
+ fprintf(stderr, "The environment variable %s is set to %s, "
+ "but we couldn't obtain from it the required function - "
+ "parse_arch_dep_event. error: %s\n",
+ PERF_ARCH_DEP_LIB_ENV_VAR, lib_name, dlerror());
+ exit(1);
+ }
+ arch_dep_lib_initialized = 1;
+}
+
static int parse_aliases(const char **str, const char *names[][MAX_ALIASES], int size)
{
int i, j;
@@ -686,6 +717,18 @@ parse_numeric_event(const char **strp, struct perf_event_attr *attr)
return EVT_FAILED;
}

+static int
+parse_arch_dep_event(const char **strp, struct perf_event_attr *attr)
+{
+ if (! arch_dep_lib_initialized)
+ initialize_arch_dep_lib();
+
+ if (arch_dep_lib_initialized)
+ return parse_arch_dep_event_callout(strp, attr);
+ else
+ return 0;
+}
+
static enum event_result
parse_event_modifier(const char **strp, struct perf_event_attr *attr)
{
@@ -724,6 +767,11 @@ parse_event_symbols(const char **str, struct perf_event_attr *attr)
{
enum event_result ret;

+ ret = parse_arch_dep_event(str, attr);
+ if (ret != EVT_FAILED)
+ /* modifiers are already processed */
+ return ret;
+
ret = parse_tracepoint_event(str, attr);
if (ret != EVT_FAILED)
goto modifier;
@@ -784,6 +832,17 @@ static int store_event_type(const char *orgname)
return perf_header__push_event(id, orgname);
}

+static char *make_substr(char *start, char *end)
+{
+ int length = end - start;
+ char *result = malloc(length + 1);
+
+ strncpy(result, start, length);
+ result[length] = '\0';
+
+ return result;
+}
+
int parse_events(const struct option *opt __used, const char *str, int unset __used)
{
struct perf_event_attr attr;
@@ -794,19 +853,23 @@ int parse_events(const struct option *opt __used, const char *str, int unset __u
return -1;

for (;;) {
+ char *start, *end;
if (nr_counters == MAX_COUNTERS)
return -1;

memset(&attr, 0, sizeof(attr));
+ start = (char *)str;
ret = parse_event_symbols(&str, &attr);
if (ret == EVT_FAILED)
return -1;

if (!(*str == 0 || *str == ',' || isspace(*str)))
return -1;
+ end = (char *)str;

if (ret != EVT_HANDLED_ALL) {
attrs[nr_counters] = attr;
+ event_names[nr_counters] = make_substr(start, end);
nr_counters++;
}
\
 
 \ /
  Last update: 2010-03-04 03:33    [W:0.139 / U:8.456 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site