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Date: Mon, 9 May 2016 18:12:39 -0300
From: Arnaldo Carvalho de Melo <acme@...hat.com>
To: Wang Nan <wangnan0@...wei.com>
Cc: acme@...nel.org, linux-kernel@...r.kernel.org, lizefan@...wei.com,
pi3orama@....com, Peter Zijlstra <peterz@...radead.org>
Subject: Re: [PATCH v3 2/2] perf tests: Add test to check backward ring buffer
Em Mon, May 09, 2016 at 01:47:51AM +0000, Wang Nan escreveu:
> This test checks reading from backward ring buffer.
>
> Test result:
>
> # ~/perf test 'ring buffer'
> 45: Test backward reading from ring buffer : Ok
Thanks, applied and also I added a patch to show that bit when using
-vv, i.e.:
# perf test -vv back
45: Test backward reading from ring buffer :
--- start ---
<SNIP>
------------------------------------------------------------
perf_event_attr:
type 2
size 112
config 0x98
{ sample_period, sample_freq } 1
sample_type IP|TID|TIME|CPU|PERIOD|RAW
disabled 1
mmap 1
comm 1
task 1
sample_id_all 1
exclude_guest 1
mmap2 1
comm_exec 1
write_backward 1
------------------------------------------------------------
<SNIP>
> Test case is a while loop which calls prctl(PR_SET_NAME) multiple
> times. Each prctl should issue 2 events: one PERF_RECORD_SAMPLE,
> one PERF_RECORD_COMM.
>
> The first round creates a relative large ring buffer (256 pages). It
> can afford all events. Read from it and check the count of each type of
> events.
>
> The second round creates a small ring buffer (1 page) and makes it
> overwritable. Check the correctness of the buffer.
>
> Signed-off-by: Wang Nan <wangnan0@...wei.com>
> Cc: Arnaldo Carvalho de Melo <acme@...hat.com>
> Cc: Peter Zijlstra <peterz@...radead.org>
> Cc: Zefan Li <lizefan@...wei.com>
> Cc: pi3orama@....com
> ---
> tools/perf/tests/Build | 1 +
> tools/perf/tests/backward-ring-buffer.c | 151 ++++++++++++++++++++++++++++++++
> tools/perf/tests/builtin-test.c | 4 +
> tools/perf/tests/tests.h | 1 +
> 4 files changed, 157 insertions(+)
> create mode 100644 tools/perf/tests/backward-ring-buffer.c
>
> diff --git a/tools/perf/tests/Build b/tools/perf/tests/Build
> index 449fe97..66a2898 100644
> --- a/tools/perf/tests/Build
> +++ b/tools/perf/tests/Build
> @@ -38,6 +38,7 @@ perf-y += cpumap.o
> perf-y += stat.o
> perf-y += event_update.o
> perf-y += event-times.o
> +perf-y += backward-ring-buffer.o
>
> $(OUTPUT)tests/llvm-src-base.c: tests/bpf-script-example.c tests/Build
> $(call rule_mkdir)
> diff --git a/tools/perf/tests/backward-ring-buffer.c b/tools/perf/tests/backward-ring-buffer.c
> new file mode 100644
> index 0000000..d9ba991
> --- /dev/null
> +++ b/tools/perf/tests/backward-ring-buffer.c
> @@ -0,0 +1,151 @@
> +/*
> + * Test backward bit in event attribute, read ring buffer from end to
> + * beginning
> + */
> +
> +#include <perf.h>
> +#include <evlist.h>
> +#include <sys/prctl.h>
> +#include "tests.h"
> +#include "debug.h"
> +
> +#define NR_ITERS 111
> +
> +static void testcase(void)
> +{
> + int i;
> +
> + for (i = 0; i < NR_ITERS; i++) {
> + char proc_name[10];
> +
> + snprintf(proc_name, sizeof(proc_name), "p:%d\n", i);
> + prctl(PR_SET_NAME, proc_name);
> + }
> +}
> +
> +static int count_samples(struct perf_evlist *evlist, int *sample_count,
> + int *comm_count)
> +{
> + int i;
> +
> + for (i = 0; i < evlist->nr_mmaps; i++) {
> + union perf_event *event;
> +
> + perf_evlist__mmap_read_catchup(evlist, i);
> + while ((event = perf_evlist__mmap_read_backward(evlist, i)) != NULL) {
> + const u32 type = event->header.type;
> +
> + switch (type) {
> + case PERF_RECORD_SAMPLE:
> + (*sample_count)++;
> + break;
> + case PERF_RECORD_COMM:
> + (*comm_count)++;
> + break;
> + default:
> + pr_err("Unexpected record of type %d\n", type);
> + return TEST_FAIL;
> + }
> + }
> + }
> + return TEST_OK;
> +}
> +
> +static int do_test(struct perf_evlist *evlist, int mmap_pages,
> + int *sample_count, int *comm_count)
> +{
> + int err;
> + char sbuf[STRERR_BUFSIZE];
> +
> + err = perf_evlist__mmap(evlist, mmap_pages, true);
> + if (err < 0) {
> + pr_debug("perf_evlist__mmap: %s\n",
> + strerror_r(errno, sbuf, sizeof(sbuf)));
> + return TEST_FAIL;
> + }
> +
> + perf_evlist__enable(evlist);
> + testcase();
> + perf_evlist__disable(evlist);
> +
> + err = count_samples(evlist, sample_count, comm_count);
> + perf_evlist__munmap(evlist);
> + return err;
> +}
> +
> +
> +int test__backward_ring_buffer(int subtest __maybe_unused)
> +{
> + int ret = TEST_SKIP, err, sample_count = 0, comm_count = 0;
> + char pid[16], sbuf[STRERR_BUFSIZE];
> + struct perf_evlist *evlist;
> + struct perf_evsel *evsel __maybe_unused;
> + struct parse_events_error parse_error;
> + struct record_opts opts = {
> + .target = {
> + .uid = UINT_MAX,
> + .uses_mmap = true,
> + },
> + .freq = 0,
> + .mmap_pages = 256,
> + .default_interval = 1,
> + };
> +
> + snprintf(pid, sizeof(pid), "%d", getpid());
> + pid[sizeof(pid) - 1] = '\0';
> + opts.target.tid = opts.target.pid = pid;
> +
> + evlist = perf_evlist__new();
> + if (!evlist) {
> + pr_debug("No ehough memory to create evlist\n");
> + return TEST_FAIL;
> + }
> +
> + err = perf_evlist__create_maps(evlist, &opts.target);
> + if (err < 0) {
> + pr_debug("Not enough memory to create thread/cpu maps\n");
> + goto out_delete_evlist;
> + }
> +
> + bzero(&parse_error, sizeof(parse_error));
> + err = parse_events(evlist, "syscalls:sys_enter_prctl", &parse_error);
> + if (err) {
> + pr_debug("Failed to parse tracepoint event, try use root\n");
> + ret = TEST_SKIP;
> + goto out_delete_evlist;
> + }
> +
> + perf_evlist__config(evlist, &opts, NULL);
> +
> + /* Set backward bit, ring buffer should be writing from end */
> + evlist__for_each(evlist, evsel)
> + evsel->attr.write_backward = 1;
> +
> + err = perf_evlist__open(evlist);
> + if (err < 0) {
> + pr_debug("perf_evlist__open: %s\n",
> + strerror_r(errno, sbuf, sizeof(sbuf)));
> + goto out_delete_evlist;
> + }
> +
> + ret = TEST_FAIL;
> + err = do_test(evlist, opts.mmap_pages, &sample_count,
> + &comm_count);
> + if (err != TEST_OK)
> + goto out_delete_evlist;
> +
> + if ((sample_count != NR_ITERS) || (comm_count != NR_ITERS)) {
> + pr_err("Unexpected counter: sample_count=%d, comm_count=%d\n",
> + sample_count, comm_count);
> + goto out_delete_evlist;
> + }
> +
> + err = do_test(evlist, 1, &sample_count, &comm_count);
> + if (err != TEST_OK)
> + goto out_delete_evlist;
> +
> + ret = TEST_OK;
> +out_delete_evlist:
> + perf_evlist__delete(evlist);
> + return ret;
> +}
> diff --git a/tools/perf/tests/builtin-test.c b/tools/perf/tests/builtin-test.c
> index 93c4670..0e95c20 100644
> --- a/tools/perf/tests/builtin-test.c
> +++ b/tools/perf/tests/builtin-test.c
> @@ -208,6 +208,10 @@ static struct test generic_tests[] = {
> .func = test__event_times,
> },
> {
> + .desc = "Test backward reading from ring buffer",
> + .func = test__backward_ring_buffer,
> + },
> + {
> .func = NULL,
> },
> };
> diff --git a/tools/perf/tests/tests.h b/tools/perf/tests/tests.h
> index 0fc9469..c57e72c 100644
> --- a/tools/perf/tests/tests.h
> +++ b/tools/perf/tests/tests.h
> @@ -86,6 +86,7 @@ int test__synthesize_stat(int subtest);
> int test__synthesize_stat_round(int subtest);
> int test__event_update(int subtest);
> int test__event_times(int subtest);
> +int test__backward_ring_buffer(int subtest);
>
> #if defined(__arm__) || defined(__aarch64__)
> #ifdef HAVE_DWARF_UNWIND_SUPPORT
> --
> 1.8.3.4
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