perf top: Improve lost events warning

Now it warns everytime that new events are lost.

And the TUI also warns now.

Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/n/tip-w1n168yrvrppnq6887s4u0wx@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

3 files changed, 44 insertions, 17 deletions

diff --git a/tools/perf/builtin-top.c b/tools/perf/builtin-top.c
index a43433f08300..23c4f71c407a 100644
--- a/tools/perf/builtin-top.c
+++ b/tools/perf/builtin-top.c
@@ -250,7 +250,7 @@ static void __list_insert_active_sym(struct sym_entry *syme)
         list_add(&syme->node, &top.active_symbols);
 }
 
-static void print_sym_table(struct perf_session *session)
+static void print_sym_table(void)
 {
         char bf[160];
         int printed = 0;
@@ -270,10 +270,11 @@ static void print_sym_table(struct perf_session *session)
 
         printf("%-*.*s\n", win_width, win_width, graph_dotted_line);
 
-        if (session->hists.stats.total_lost != 0) {
+        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",
-                       session->hists.stats.total_lost);
+                       top.total_lost_warned);
         }
 
         if (top.sym_filter_entry) {
@@ -474,7 +475,7 @@ static int key_mapped(int c)
         return 0;
 }
 
-static void handle_keypress(struct perf_session *session, int c)
+static void handle_keypress(int c)
 {
         if (!key_mapped(c)) {
                 struct pollfd stdin_poll = { .fd = 0, .events = POLLIN };
@@ -550,7 +551,7 @@ static void handle_keypress(struct perf_session *session, int c)
                 case 'Q':
                         printf("exiting.\n");
                         if (dump_symtab)
-                                perf_session__fprintf_dsos(session, stderr);
+                                perf_session__fprintf_dsos(top.session, stderr);
                         exit(0);
                 case 's':
                         prompt_symbol(&top.sym_filter_entry, "Enter details symbol");
@@ -602,7 +603,6 @@ static void *display_thread(void *arg __used)
         struct pollfd stdin_poll = { .fd = 0, .events = POLLIN };
         struct termios tc, save;
         int delay_msecs, c;
-        struct perf_session *session = (struct perf_session *) arg;
 
         tcgetattr(0, &save);
         tc = save;
@@ -617,13 +617,13 @@ repeat:
         getc(stdin);
 
         do {
-                print_sym_table(session);
+                print_sym_table();
         } while (!poll(&stdin_poll, 1, delay_msecs) == 1);
 
         c = getc(stdin);
         tcsetattr(0, TCSAFLUSH, &save);
 
-        handle_keypress(session, c);
+        handle_keypress(c);
         goto repeat;
 
         return NULL;
@@ -935,27 +935,27 @@ static int __cmd_top(void)
          * FIXME: perf_session__new should allow passing a O_MMAP, so that all this
          * mmap reading, etc is encapsulated in it. Use O_WRONLY for now.
          */
-        struct perf_session *session = perf_session__new(NULL, O_WRONLY, false, false, NULL);
-        if (session == NULL)
+        top.session = perf_session__new(NULL, O_WRONLY, false, false, NULL);
+        if (top.session == NULL)
                 return -ENOMEM;
 
         if (top.target_tid != -1)
                 perf_event__synthesize_thread_map(top.evlist->threads,
-                                                  perf_event__process, session);
+                                                  perf_event__process, top.session);
         else
-                perf_event__synthesize_threads(perf_event__process, session);
+                perf_event__synthesize_threads(perf_event__process, top.session);
 
         start_counters(top.evlist);
-        session->evlist = top.evlist;
-        perf_session__update_sample_type(session);
+        top.session->evlist = top.evlist;
+        perf_session__update_sample_type(top.session);
 
         /* Wait for a minimal set of events before starting the snapshot */
         poll(top.evlist->pollfd, top.evlist->nr_fds, 100);
 
-        perf_session__mmap_read(session);
+        perf_session__mmap_read(top.session);
 
         if (pthread_create(&thread, NULL, (use_browser > 0 ? display_thread_tui :
-                                                             display_thread), session)) {
+                                                             display_thread), NULL)) {
                 printf("Could not create display thread.\n");
                 exit(-1);
         }
@@ -973,7 +973,7 @@ static int __cmd_top(void)
         while (1) {
                 u64 hits = top.samples;
 
-                perf_session__mmap_read(session);
+                perf_session__mmap_read(top.session);
 
                 if (hits == top.samples)
                         ret = poll(top.evlist->pollfd, top.evlist->nr_fds, 100);
diff --git a/tools/perf/util/top.h b/tools/perf/util/top.h
index bfbf95bcc603..b07b0410463c 100644
--- a/tools/perf/util/top.h
+++ b/tools/perf/util/top.h
@@ -10,6 +10,7 @@
 
 struct perf_evlist;
 struct perf_evsel;
+struct perf_session;
 
 struct sym_entry {
         struct rb_node          rb_node;
@@ -38,6 +39,7 @@ 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                display_weighted, freq, rb_entries;
         pid_t              target_pid, target_tid;
@@ -45,6 +47,7 @@ struct perf_top {
         const char         *cpu_list;
         struct sym_entry   *sym_filter_entry;
         struct perf_evsel  *sym_evsel;
+        struct perf_session *session;
 };
 
 size_t perf_top__header_snprintf(struct perf_top *top, char *bf, size_t size);
diff --git a/tools/perf/util/ui/browsers/top.c b/tools/perf/util/ui/browsers/top.c
index 9d938106510f..9b6b43b32ac8 100644
--- a/tools/perf/util/ui/browsers/top.c
+++ b/tools/perf/util/ui/browsers/top.c
@@ -11,10 +11,12 @@
 #include "../helpline.h"
 #include "../libslang.h"
 #include "../util.h"
+#include "../ui.h"
 #include "../../evlist.h"
 #include "../../hist.h"
 #include "../../sort.h"
 #include "../../symbol.h"
+#include "../../session.h"
 #include "../../top.h"
 
 struct perf_top_browser {
@@ -143,6 +145,25 @@ do_annotation:
         symbol__tui_annotate(sym, syme->map, 0, top->delay_secs * 1000);
 }
 
+static void perf_top_browser__warn_lost(struct perf_top_browser *browser)
+{
+        struct perf_top *top = browser->b.priv;
+        char msg[128];
+        int len;
+
+        top->total_lost_warned = top->session->hists.stats.total_lost;
+        pthread_mutex_lock(&ui__lock);
+        ui_browser__set_color(&browser->b, HE_COLORSET_TOP);
+        len = snprintf(msg, sizeof(msg),
+                      " WARNING: LOST %" PRIu64 " events, Check IO/CPU overload",
+                      top->total_lost_warned);
+        if (len > browser->b.width)
+                len = browser->b.width;
+        SLsmg_gotorc(0, browser->b.width - len);
+        slsmg_write_nstring(msg, len);
+        pthread_mutex_unlock(&ui__lock);
+}
+
 static int perf_top_browser__run(struct perf_top_browser *browser)
 {
         int key;
@@ -174,6 +195,9 @@ static int perf_top_browser__run(struct perf_top_browser *browser)
                         ui_browser__set_color(&browser->b, NEWT_COLORSET_ROOT);
                         SLsmg_gotorc(0, 0);
                         slsmg_write_nstring(title, browser->b.width);
+
+                        if (top->total_lost_warned != top->session->hists.stats.total_lost)
+                                perf_top_browser__warn_lost(browser);
                         break;
                 case 'a':
                 case NEWT_KEY_RIGHT: