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author | Jiri Olsa <jolsa@kernel.org> | 2019-03-14 15:00:10 +0100 |
---|---|---|
committer | Arnaldo Carvalho de Melo <acme@redhat.com> | 2019-03-28 14:31:56 -0300 |
commit | 4e8a5c1551370ebc0fbdb8f5c33dad13e45bdc99 (patch) | |
tree | 01eb53d2f8acac91aa73fa9ee3649ba849e0c1d2 /tools/perf/util/evsel.c | |
parent | f3b4e06b3bda759afd042d3d5fa86bea8f1fe278 (diff) | |
download | linux-4e8a5c1551370ebc0fbdb8f5c33dad13e45bdc99.tar.bz2 |
perf evsel: Fix max perf_event_attr.precise_ip detection
After a discussion with Andi, move the perf_event_attr.precise_ip
detection for maximum precise config (via :P modifier or for default
cycles event) to perf_evsel__open().
The current detection in perf_event_attr__set_max_precise_ip() is
tricky, because precise_ip config is specific for given event and it
currently checks only hw cycles.
We now check for valid precise_ip value right after failing
sys_perf_event_open() for specific event, before any of the
perf_event_attr fallback code gets executed.
This way we get the proper config in perf_event_attr together with
allowed precise_ip settings.
We can see that code activity with -vv, like:
$ perf record -vv ls
...
------------------------------------------------------------
perf_event_attr:
size 112
{ sample_period, sample_freq } 4000
...
precise_ip 3
sample_id_all 1
exclude_guest 1
mmap2 1
comm_exec 1
ksymbol 1
------------------------------------------------------------
sys_perf_event_open: pid 9926 cpu 0 group_fd -1 flags 0x8
sys_perf_event_open failed, error -95
decreasing precise_ip by one (2)
------------------------------------------------------------
perf_event_attr:
size 112
{ sample_period, sample_freq } 4000
...
precise_ip 2
sample_id_all 1
exclude_guest 1
mmap2 1
comm_exec 1
ksymbol 1
------------------------------------------------------------
sys_perf_event_open: pid 9926 cpu 0 group_fd -1 flags 0x8 = 4
...
Suggested-by: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Link: http://lkml.kernel.org/n/tip-dkvxxbeg7lu74155d4jhlmc9@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Diffstat (limited to 'tools/perf/util/evsel.c')
-rw-r--r-- | tools/perf/util/evsel.c | 72 |
1 files changed, 59 insertions, 13 deletions
diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c index 7835e05f0c0a..66d066f18b5b 100644 --- a/tools/perf/util/evsel.c +++ b/tools/perf/util/evsel.c @@ -295,7 +295,6 @@ struct perf_evsel *perf_evsel__new_cycles(bool precise) if (!precise) goto new_event; - perf_event_attr__set_max_precise_ip(&attr); /* * Now let the usual logic to set up the perf_event_attr defaults * to kick in when we return and before perf_evsel__open() is called. @@ -305,6 +304,8 @@ new_event: if (evsel == NULL) goto out; + evsel->precise_max = true; + /* use asprintf() because free(evsel) assumes name is allocated */ if (asprintf(&evsel->name, "cycles%s%s%.*s", (attr.precise_ip || attr.exclude_kernel) ? ":" : "", @@ -1083,7 +1084,7 @@ void perf_evsel__config(struct perf_evsel *evsel, struct record_opts *opts, } if (evsel->precise_max) - perf_event_attr__set_max_precise_ip(attr); + attr->precise_ip = 3; if (opts->all_user) { attr->exclude_kernel = 1; @@ -1749,6 +1750,59 @@ static bool ignore_missing_thread(struct perf_evsel *evsel, return true; } +static void display_attr(struct perf_event_attr *attr) +{ + if (verbose >= 2) { + fprintf(stderr, "%.60s\n", graph_dotted_line); + fprintf(stderr, "perf_event_attr:\n"); + perf_event_attr__fprintf(stderr, attr, __open_attr__fprintf, NULL); + fprintf(stderr, "%.60s\n", graph_dotted_line); + } +} + +static int perf_event_open(struct perf_evsel *evsel, + pid_t pid, int cpu, int group_fd, + unsigned long flags) +{ + int precise_ip = evsel->attr.precise_ip; + int fd; + + while (1) { + pr_debug2("sys_perf_event_open: pid %d cpu %d group_fd %d flags %#lx", + pid, cpu, group_fd, flags); + + fd = sys_perf_event_open(&evsel->attr, pid, cpu, group_fd, flags); + if (fd >= 0) + break; + + /* + * Do quick precise_ip fallback if: + * - there is precise_ip set in perf_event_attr + * - maximum precise is requested + * - sys_perf_event_open failed with ENOTSUP error, + * which is associated with wrong precise_ip + */ + if (!precise_ip || !evsel->precise_max || (errno != ENOTSUP)) + break; + + /* + * We tried all the precise_ip values, and it's + * still failing, so leave it to standard fallback. + */ + if (!evsel->attr.precise_ip) { + evsel->attr.precise_ip = precise_ip; + break; + } + + pr_debug2("\nsys_perf_event_open failed, error %d\n", -ENOTSUP); + evsel->attr.precise_ip--; + pr_debug2("decreasing precise_ip by one (%d)\n", evsel->attr.precise_ip); + display_attr(&evsel->attr); + } + + return fd; +} + int perf_evsel__open(struct perf_evsel *evsel, struct cpu_map *cpus, struct thread_map *threads) { @@ -1824,12 +1878,7 @@ retry_sample_id: if (perf_missing_features.sample_id_all) evsel->attr.sample_id_all = 0; - if (verbose >= 2) { - fprintf(stderr, "%.60s\n", graph_dotted_line); - fprintf(stderr, "perf_event_attr:\n"); - perf_event_attr__fprintf(stderr, &evsel->attr, __open_attr__fprintf, NULL); - fprintf(stderr, "%.60s\n", graph_dotted_line); - } + display_attr(&evsel->attr); for (cpu = 0; cpu < cpus->nr; cpu++) { @@ -1841,13 +1890,10 @@ retry_sample_id: group_fd = get_group_fd(evsel, cpu, thread); retry_open: - pr_debug2("sys_perf_event_open: pid %d cpu %d group_fd %d flags %#lx", - pid, cpus->map[cpu], group_fd, flags); - test_attr__ready(); - fd = sys_perf_event_open(&evsel->attr, pid, cpus->map[cpu], - group_fd, flags); + fd = perf_event_open(evsel, pid, cpus->map[cpu], + group_fd, flags); FD(evsel, cpu, thread) = fd; |