[PATCH 2/3] perf hists browser: Warn about lost events

From: Arnaldo Carvalho de Melo
Date: Sat Oct 29 2011 - 13:26:13 EST


From: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>

Just like the old perf top --tui and the --stdio version.

But because we have the initial menu to choose which event to show in a
session with multiple events we can see how many chunks were lost in
each of the event types, clarifying which events are being affected the
most.

Cc: David Ahern <dsahern@xxxxxxxxx>
Cc: Frederic Weisbecker <fweisbec@xxxxxxxxx>
Cc: Mike Galbraith <efault@xxxxxx>
Cc: Paul Mackerras <paulus@xxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Stephane Eranian <eranian@xxxxxxxxxx>
Link: http://lkml.kernel.org/n/tip-todvhe1xle9f0z2gf8jiyvxj@xxxxxxxxxxxxxx
Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
---
tools/perf/builtin-top.c | 41 +++++++++++++++++++++--------
tools/perf/util/hist.h | 1 +
tools/perf/util/session.c | 29 ++++++++++++++++----
tools/perf/util/top.h | 1 -
tools/perf/util/ui/browser.c | 21 ++++++++++++---
tools/perf/util/ui/browser.h | 3 +-
tools/perf/util/ui/browsers/hists.c | 49 ++++++++++++++++++++++++++++++----
7 files changed, 116 insertions(+), 29 deletions(-)

diff --git a/tools/perf/builtin-top.c b/tools/perf/builtin-top.c
index 31aa82c..c8d31d9 100644
--- a/tools/perf/builtin-top.c
+++ b/tools/perf/builtin-top.c
@@ -89,6 +89,7 @@ static bool vmlinux_warned;
static bool inherit = false;
static int realtime_prio = 0;
static bool group = false;
+static bool sample_id_all_avail = true;
static unsigned int mmap_pages = 128;

static bool dump_symtab = false;
@@ -289,11 +290,13 @@ static void print_sym_table(void)

printf("%-*.*s\n", win_width, win_width, graph_dotted_line);

- if (top.total_lost_warned != top.session->hists.stats.total_lost) {
- top.total_lost_warned = top.session->hists.stats.total_lost;
- color_fprintf(stdout, PERF_COLOR_RED, "WARNING:");
- printf(" LOST %" PRIu64 " events, Check IO/CPU overload\n",
- top.total_lost_warned);
+ if (top.sym_evsel->hists.stats.nr_lost_warned !=
+ top.sym_evsel->hists.stats.nr_events[PERF_RECORD_LOST]) {
+ top.sym_evsel->hists.stats.nr_lost_warned =
+ top.sym_evsel->hists.stats.nr_events[PERF_RECORD_LOST];
+ color_fprintf(stdout, PERF_COLOR_RED,
+ "WARNING: LOST %d chunks, Check IO/CPU overload",
+ top.sym_evsel->hists.stats.nr_lost_warned);
++printed;
}

@@ -671,6 +674,7 @@ static int symbol_filter(struct map *map __used, struct symbol *sym)
}

static void perf_event__process_sample(const union perf_event *event,
+ struct perf_evsel *evsel,
struct perf_sample *sample,
struct perf_session *session)
{
@@ -770,12 +774,8 @@ static void perf_event__process_sample(const union perf_event *event,
}

if (al.sym == NULL || !al.sym->ignore) {
- struct perf_evsel *evsel;
struct hist_entry *he;

- evsel = perf_evlist__id2evsel(top.evlist, sample->id);
- assert(evsel != NULL);
-
if ((sort__has_parent || symbol_conf.use_callchain) &&
sample->callchain) {
err = perf_session__resolve_callchain(session, al.thread,
@@ -807,10 +807,13 @@ static void perf_event__process_sample(const union perf_event *event,
static void perf_session__mmap_read_idx(struct perf_session *self, int idx)
{
struct perf_sample sample;
+ struct perf_evsel *evsel;
union perf_event *event;
int ret;

while ((event = perf_evlist__mmap_read(top.evlist, idx)) != NULL) {
+ u64 id;
+
ret = perf_session__parse_sample(self, event, &sample);
if (ret) {
pr_err("Can't parse sample, err = %d\n", ret);
@@ -818,9 +821,17 @@ static void perf_session__mmap_read_idx(struct perf_session *self, int idx)
}

if (event->header.type == PERF_RECORD_SAMPLE)
- perf_event__process_sample(event, &sample, self);
- else
+ id = sample.id;
+ evsel = perf_evlist__id2evsel(self->evlist, sample.id);
+ assert(evsel != NULL);
+
+ if (event->header.type == PERF_RECORD_SAMPLE)
+ perf_event__process_sample(event, evsel, &sample, self);
+ else if (event->header.type < PERF_RECORD_MAX) {
+ hists__inc_nr_events(&evsel->hists, event->header.type);
perf_event__process(event, &sample, self);
+ } else
+ ++self->hists.stats.nr_unknown_events;
}
}

@@ -864,6 +875,8 @@ static void start_counters(struct perf_evlist *evlist)
attr->mmap = 1;
attr->comm = 1;
attr->inherit = inherit;
+retry_sample_id:
+ attr->sample_id_all = sample_id_all_avail ? 1 : 0;
try_again:
if (perf_evsel__open(counter, top.evlist->cpus,
top.evlist->threads, group,
@@ -873,6 +886,12 @@ try_again:
if (err == EPERM || err == EACCES) {
ui__error_paranoid();
goto out_err;
+ } else if (err == EINVAL && sample_id_all_avail) {
+ /*
+ * Old kernel, no attr->sample_id_type_all field
+ */
+ sample_id_all_avail = false;
+ goto retry_sample_id;
}
/*
* If it's cycles then fall back to hrtimer
diff --git a/tools/perf/util/hist.h b/tools/perf/util/hist.h
index ff93ddc..c86c1d2 100644
--- a/tools/perf/util/hist.h
+++ b/tools/perf/util/hist.h
@@ -28,6 +28,7 @@ struct events_stats {
u64 total_lost;
u64 total_invalid_chains;
u32 nr_events[PERF_RECORD_HEADER_MAX];
+ u32 nr_lost_warned;
u32 nr_unknown_events;
u32 nr_invalid_chains;
u32 nr_unknown_id;
diff --git a/tools/perf/util/session.c b/tools/perf/util/session.c
index 91c6442..da354fe 100644
--- a/tools/perf/util/session.c
+++ b/tools/perf/util/session.c
@@ -738,10 +738,27 @@ static int perf_session_deliver_event(struct perf_session *session,

dump_event(session, event, file_offset, sample);

+ evsel = perf_evlist__id2evsel(session->evlist, sample->id);
+ if (evsel != NULL && event->header.type != PERF_RECORD_SAMPLE) {
+ /*
+ * XXX We're leaving PERF_RECORD_SAMPLE unnacounted here
+ * because the tools right now may apply filters, discarding
+ * some of the samples. For consistency, in the future we
+ * should have something like nr_filtered_samples and remove
+ * the sample->period from total_sample_period, etc, KISS for
+ * now tho.
+ *
+ * Also testing against NULL allows us to handle files without
+ * attr.sample_id_all and/or without PERF_SAMPLE_ID. In the
+ * future probably it'll be a good idea to restrict event
+ * processing via perf_session to files with both set.
+ */
+ hists__inc_nr_events(&evsel->hists, event->header.type);
+ }
+
switch (event->header.type) {
case PERF_RECORD_SAMPLE:
dump_sample(session, event, sample);
- evsel = perf_evlist__id2evsel(session->evlist, sample->id);
if (evsel == NULL) {
++session->hists.stats.nr_unknown_id;
return -1;
@@ -874,11 +891,11 @@ static void perf_session__warn_about_errors(const struct perf_session *session,
const struct perf_event_ops *ops)
{
if (ops->lost == perf_event__process_lost &&
- session->hists.stats.total_lost != 0) {
- ui__warning("Processed %" PRIu64 " events and LOST %" PRIu64
- "!\n\nCheck IO/CPU overload!\n\n",
- session->hists.stats.total_period,
- session->hists.stats.total_lost);
+ session->hists.stats.nr_events[PERF_RECORD_LOST] != 0) {
+ ui__warning("Processed %d events and lost %d chunks!\n\n"
+ "Check IO/CPU overload!\n\n",
+ session->hists.stats.nr_events[0],
+ session->hists.stats.nr_events[PERF_RECORD_LOST]);
}

if (session->hists.stats.nr_unknown_events != 0) {
diff --git a/tools/perf/util/top.h b/tools/perf/util/top.h
index 01d1057..3996509 100644
--- a/tools/perf/util/top.h
+++ b/tools/perf/util/top.h
@@ -19,7 +19,6 @@ struct perf_top {
u64 kernel_samples, us_samples;
u64 exact_samples;
u64 guest_us_samples, guest_kernel_samples;
- u64 total_lost_warned;
int print_entries, count_filter, delay_secs;
int freq;
pid_t target_pid, target_tid;
diff --git a/tools/perf/util/ui/browser.c b/tools/perf/util/ui/browser.c
index d2051be..5568291 100644
--- a/tools/perf/util/ui/browser.c
+++ b/tools/perf/util/ui/browser.c
@@ -176,16 +176,29 @@ void ui_browser__handle_resize(struct ui_browser *browser)
ui_browser__refresh(browser);
}

-int ui_browser__warning(struct ui_browser *browser, const char *format, ...)
+int ui_browser__warning(struct ui_browser *browser, int timeout,
+ const char *format, ...)
{
va_list args;
- int key;
+ char *text;
+ int key = 0, err;

va_start(args, format);
- while ((key = __ui__warning("Warning!", format, args)) == K_RESIZE)
- ui_browser__handle_resize(browser);
+ err = vasprintf(&text, format, args);
va_end(args);

+ if (err < 0) {
+ va_start(args, format);
+ ui_helpline__vpush(format, args);
+ va_end(args);
+ } else {
+ while ((key == ui__question_window("Warning!", text,
+ "Press any key...",
+ timeout)) == K_RESIZE)
+ ui_browser__handle_resize(browser);
+ free(text);
+ }
+
return key;
}

diff --git a/tools/perf/util/ui/browser.h b/tools/perf/util/ui/browser.h
index fb1c598..84d761b 100644
--- a/tools/perf/util/ui/browser.h
+++ b/tools/perf/util/ui/browser.h
@@ -45,7 +45,8 @@ int ui_browser__run(struct ui_browser *browser, int delay_secs);
void ui_browser__update_nr_entries(struct ui_browser *browser, u32 nr_entries);
void ui_browser__handle_resize(struct ui_browser *browser);

-int ui_browser__warning(struct ui_browser *browser, const char *format, ...);
+int ui_browser__warning(struct ui_browser *browser, int timeout,
+ const char *format, ...);
int ui_browser__help_window(struct ui_browser *browser, const char *text);
bool ui_browser__dialog_yesno(struct ui_browser *browser, const char *text);

diff --git a/tools/perf/util/ui/browsers/hists.c b/tools/perf/util/ui/browsers/hists.c
index b8733c0..d0c94b4 100644
--- a/tools/perf/util/ui/browsers/hists.c
+++ b/tools/perf/util/ui/browsers/hists.c
@@ -295,6 +295,15 @@ static void hist_browser__set_folding(struct hist_browser *self, bool unfold)
ui_browser__reset_index(&self->b);
}

+static void ui_browser__warn_lost_events(struct ui_browser *browser)
+{
+ ui_browser__warning(browser, 4,
+ "Events are being lost, check IO/CPU overload!\n\n"
+ "You may want to run 'perf' using a RT scheduler policy:\n\n"
+ " perf top -r 80\n\n"
+ "Or reduce the sampling frequency.");
+}
+
static int hist_browser__run(struct hist_browser *self, const char *ev_name,
void(*timer)(void *arg), void *arg, int delay_secs)
{
@@ -318,8 +327,15 @@ static int hist_browser__run(struct hist_browser *self, const char *ev_name,
case K_TIMER:
timer(arg);
ui_browser__update_nr_entries(&self->b, self->hists->nr_entries);
- hists__browser_title(self->hists, title, sizeof(title),
- ev_name);
+
+ if (self->hists->stats.nr_lost_warned !=
+ self->hists->stats.nr_events[PERF_RECORD_LOST]) {
+ self->hists->stats.nr_lost_warned =
+ self->hists->stats.nr_events[PERF_RECORD_LOST];
+ ui_browser__warn_lost_events(&self->b);
+ }
+
+ hists__browser_title(self->hists, title, sizeof(title), ev_name);
ui_browser__show_title(&self->b, title);
continue;
case 'D': { /* Debug */
@@ -883,7 +899,7 @@ static int perf_evsel__hists_browse(struct perf_evsel *evsel, int nr_events,
goto out_free_stack;
case 'a':
if (!browser->has_symbols) {
- ui_browser__warning(&browser->b,
+ ui_browser__warning(&browser->b, delay_secs * 2,
"Annotation is only available for symbolic views, "
"include \"sym\" in --sort to use it.");
continue;
@@ -1061,6 +1077,7 @@ out:
struct perf_evsel_menu {
struct ui_browser b;
struct perf_evsel *selection;
+ bool lost_events, lost_events_warned;
};

static void perf_evsel_menu__write(struct ui_browser *browser,
@@ -1073,14 +1090,29 @@ static void perf_evsel_menu__write(struct ui_browser *browser,
unsigned long nr_events = evsel->hists.stats.nr_events[PERF_RECORD_SAMPLE];
const char *ev_name = event_name(evsel);
char bf[256], unit;
+ const char *warn = " ";
+ size_t printed;

ui_browser__set_color(browser, current_entry ? HE_COLORSET_SELECTED :
HE_COLORSET_NORMAL);

nr_events = convert_unit(nr_events, &unit);
- snprintf(bf, sizeof(bf), "%lu%c%s%s", nr_events,
- unit, unit == ' ' ? "" : " ", ev_name);
- slsmg_write_nstring(bf, browser->width);
+ printed = snprintf(bf, sizeof(bf), "%lu%c%s%s", nr_events,
+ unit, unit == ' ' ? "" : " ", ev_name);
+ slsmg_printf("%s", bf);
+
+ nr_events = evsel->hists.stats.nr_events[PERF_RECORD_LOST];
+ if (nr_events != 0) {
+ menu->lost_events = true;
+ if (!current_entry)
+ ui_browser__set_color(browser, HE_COLORSET_TOP);
+ nr_events = convert_unit(nr_events, &unit);
+ snprintf(bf, sizeof(bf), ": %ld%c%schunks LOST!", nr_events,
+ unit, unit == ' ' ? "" : " ");
+ warn = bf;
+ }
+
+ slsmg_write_nstring(warn, browser->width - printed);

if (current_entry)
menu->selection = evsel;
@@ -1105,6 +1137,11 @@ static int perf_evsel_menu__run(struct perf_evsel_menu *menu,
switch (key) {
case K_TIMER:
timer(arg);
+
+ if (!menu->lost_events_warned && menu->lost_events) {
+ ui_browser__warn_lost_events(&menu->b);
+ menu->lost_events_warned = true;
+ }
continue;
case K_RIGHT:
case K_ENTER:
--
1.6.2.5

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