perf pmu: Parse sysfs events directly from a file

Rather than read a sysfs events file into a 256 byte char buffer, pass
the FILE* directly to the lex/yacc parser.

This avoids there being a maximum events file size.

While changing the API, constify some arguments to remove unnecessary
casts.

Allocating the read buffer decreases the performance of pmu-scan by
around 3%.

Signed-off-by: Ian Rogers <irogers@google.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Gaosheng Cui <cuigaosheng1@huawei.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Clark <james.clark@arm.com>
Cc: Jing Zhang <renyu.zj@linux.alibaba.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: John Garry <john.g.garry@oracle.com>
Cc: Kajol Jain <kjain@linux.ibm.com>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ravi Bangoria <ravi.bangoria@amd.com>
Cc: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20230824041330.266337-10-irogers@google.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

diff --git a/tools/perf/arch/x86/util/intel-pt.c b/tools/perf/arch/x86/util/intel-pt.c
index 27944c1..3180779 100644 (file)
--- a/tools/perf/arch/x86/util/intel-pt.c
+++ b/tools/perf/arch/x86/util/intel-pt.c
@@ -74,7 +74,7 @@ static int intel_pt_parse_terms_with_default(struct perf_pmu *pmu,
 
        INIT_LIST_HEAD(terms);
 
-       err = parse_events_terms(terms, str);
+       err = parse_events_terms(terms, str, /*input=*/ NULL);
        if (err)
                goto out_free;
 

diff --git a/tools/perf/tests/parse-events.c b/tools/perf/tests/parse-events.c
index 658fb95..d86076d 100644 (file)
--- a/tools/perf/tests/parse-events.c
+++ b/tools/perf/tests/parse-events.c
@@ -2472,7 +2472,7 @@ static int test_term(const struct terms_test *t)
 
        INIT_LIST_HEAD(&terms);
 
-       ret = parse_events_terms(&terms, t->str);
+       ret = parse_events_terms(&terms, t->str, /*input=*/ NULL);
        if (ret) {
                pr_debug("failed to parse terms '%s', err %d\n",
                         t->str , ret);

diff --git a/tools/perf/util/parse-events.c b/tools/perf/util/parse-events.c
index 781747b..c71e135 100644 (file)
--- a/tools/perf/util/parse-events.c
+++ b/tools/perf/util/parse-events.c
@@ -1715,6 +1715,7 @@ int parse_events_name(struct list_head *list, const char *name)
 }
 
 static int parse_events__scanner(const char *str,
+                                FILE *input,
                                 struct parse_events_state *parse_state)
 {
        YY_BUFFER_STATE buffer;
@@ -1725,7 +1726,10 @@ static int parse_events__scanner(const char *str,
        if (ret)
                return ret;
 
-       buffer = parse_events__scan_string(str, scanner);
+       if (str)
+               buffer = parse_events__scan_string(str, scanner);
+       else
+               parse_events_set_in(input, scanner);
 
 #ifdef PARSER_DEBUG
        parse_events_debug = 1;
@@ -1733,8 +1737,10 @@ static int parse_events__scanner(const char *str,
 #endif
        ret = parse_events_parse(parse_state, scanner);
 
-       parse_events__flush_buffer(buffer, scanner);
-       parse_events__delete_buffer(buffer, scanner);
+       if (str) {
+               parse_events__flush_buffer(buffer, scanner);
+               parse_events__delete_buffer(buffer, scanner);
+       }
        parse_events_lex_destroy(scanner);
        return ret;
 }
@@ -1742,7 +1748,7 @@ static int parse_events__scanner(const char *str,
 /*
  * parse event config string, return a list of event terms.
  */
-int parse_events_terms(struct list_head *terms, const char *str)
+int parse_events_terms(struct list_head *terms, const char *str, FILE *input)
 {
        struct parse_events_state parse_state = {
                .terms  = NULL,
@@ -1750,7 +1756,7 @@ int parse_events_terms(struct list_head *terms, const char *str)
        };
        int ret;
 
-       ret = parse_events__scanner(str, &parse_state);
+       ret = parse_events__scanner(str, input, &parse_state);
 
        if (!ret) {
                list_splice(parse_state.terms, terms);
@@ -2001,7 +2007,7 @@ int __parse_events(struct evlist *evlist, const char *str, const char *pmu_filte
        };
        int ret, ret2;
 
-       ret = parse_events__scanner(str, &parse_state);
+       ret = parse_events__scanner(str, /*input=*/ NULL, &parse_state);
 
        if (!ret && list_empty(&parse_state.list)) {
                WARN_ONCE(true, "WARNING: event parser found nothing\n");

diff --git a/tools/perf/util/parse-events.h b/tools/perf/util/parse-events.h
index 411f69b..c7f7794 100644 (file)
--- a/tools/perf/util/parse-events.h
+++ b/tools/perf/util/parse-events.h
@@ -9,6 +9,7 @@
 #include <stdbool.h>
 #include <linux/types.h>
 #include <linux/perf_event.h>
+#include <stdio.h>
 #include <string.h>
 
 struct evsel;
@@ -42,7 +43,7 @@ static inline int parse_events(struct evlist *evlist, const char *str,
 
 int parse_event(struct evlist *evlist, const char *str);
 
-int parse_events_terms(struct list_head *terms, const char *str);
+int parse_events_terms(struct list_head *terms, const char *str, FILE *input);
 int parse_filter(const struct option *opt, const char *str, int unset);
 int exclude_perf(const struct option *opt, const char *arg, int unset);
 

diff --git a/tools/perf/util/pmu.c b/tools/perf/util/pmu.c
index 9ba9ac3..263c63e 100644 (file)
--- a/tools/perf/util/pmu.c
+++ b/tools/perf/util/pmu.c
@@ -280,7 +280,7 @@ out:
        return ret;
 }
 
-static int perf_pmu__parse_scale(struct perf_pmu_alias *alias, int dirfd, char *name)
+static int perf_pmu__parse_scale(struct perf_pmu_alias *alias, int dirfd, const char *name)
 {
        struct stat st;
        ssize_t sret;
@@ -312,7 +312,7 @@ error:
        return ret;
 }
 
-static int perf_pmu__parse_unit(struct perf_pmu_alias *alias, int dirfd, char *name)
+static int perf_pmu__parse_unit(struct perf_pmu_alias *alias, int dirfd, const char *name)
 {
        char path[PATH_MAX];
        ssize_t sret;
@@ -343,7 +343,7 @@ error:
 }
 
 static int
-perf_pmu__parse_per_pkg(struct perf_pmu_alias *alias, int dirfd, char *name)
+perf_pmu__parse_per_pkg(struct perf_pmu_alias *alias, int dirfd, const char *name)
 {
        char path[PATH_MAX];
        int fd;
@@ -361,7 +361,7 @@ perf_pmu__parse_per_pkg(struct perf_pmu_alias *alias, int dirfd, char *name)
 }
 
 static int perf_pmu__parse_snapshot(struct perf_pmu_alias *alias,
-                                   int dirfd, char *name)
+                                   int dirfd, const char *name)
 {
        char path[PATH_MAX];
        int fd;
@@ -454,8 +454,9 @@ static bool perf_pmu_merge_alias(struct perf_pmu_alias *newalias,
        return false;
 }
 
-static int __perf_pmu__new_alias(struct list_head *list, int dirfd, char *name,
-                                char *desc, char *val, const struct pmu_event *pe)
+static int perf_pmu__new_alias(struct list_head *list, int dirfd, const char *name,
+                               const char *desc, const char *val, FILE *val_fd,
+                               const struct pmu_event *pe)
 {
        struct parse_events_term *term;
        struct perf_pmu_alias *alias;
@@ -484,7 +485,7 @@ static int __perf_pmu__new_alias(struct list_head *list, int dirfd, char *name,
        alias->snapshot = false;
        alias->deprecated = deprecated;
 
-       ret = parse_events_terms(&alias->terms, val);
+       ret = parse_events_terms(&alias->terms, val, val_fd);
        if (ret) {
                pr_err("Cannot parse alias %s: %d\n", val, ret);
                free(alias);
@@ -541,23 +542,6 @@ static int __perf_pmu__new_alias(struct list_head *list, int dirfd, char *name,
        return 0;
 }
 
-static int perf_pmu__new_alias(struct list_head *list, int dirfd, char *name, FILE *file)
-{
-       char buf[256];
-       int ret;
-
-       ret = fread(buf, 1, sizeof(buf), file);
-       if (ret == 0)
-               return -EINVAL;
-
-       buf[ret] = 0;
-
-       /* Remove trailing newline from sysfs file */
-       strim(buf);
-
-       return __perf_pmu__new_alias(list, dirfd, name, NULL, buf, NULL);
-}
-
 static inline bool pmu_alias_info_file(char *name)
 {
        size_t len;
@@ -613,7 +597,8 @@ static int pmu_aliases_parse(int dirfd, struct list_head *head)
                        continue;
                }
 
-               if (perf_pmu__new_alias(head, dirfd, name, file) < 0)
+               if (perf_pmu__new_alias(head, dirfd, name, /*desc=*/ NULL,
+                                       /*val=*/ NULL, file, /*pe=*/ NULL) < 0)
                        pr_debug("Cannot set up %s\n", name);
                fclose(file);
        }
@@ -866,7 +851,7 @@ static int pmu_add_cpu_aliases_map_callback(const struct pmu_event *pe,
        struct list_head *head = vdata;
 
        /* need type casts to override 'const' */
-       __perf_pmu__new_alias(head, -1, (char *)pe->name, (char *)pe->desc, (char *)pe->event, pe);
+       perf_pmu__new_alias(head, -1, pe->name, pe->desc, pe->event, /*val_fd=*/ NULL, pe);
        return 0;
 }
 
@@ -907,11 +892,12 @@ static int pmu_add_sys_aliases_iter_fn(const struct pmu_event *pe,
 
        if (!strcmp(pmu->id, pe->compat) &&
            pmu_uncore_alias_match(pe->pmu, pmu->name)) {
-               __perf_pmu__new_alias(idata->head, -1,
-                                     (char *)pe->name,
-                                     (char *)pe->desc,
-                                     (char *)pe->event,
-                                     pe);
+               perf_pmu__new_alias(idata->head, -1,
+                               pe->name,
+                               pe->desc,
+                               pe->event,
+                               /*val_fd=*/ NULL,
+                               pe);
        }
 
        return 0;