tools/delaytop: add interactive mode with keyboard controls

The original delaytop only supported static output with limited
interaction.  Users had to restart the tool with different command-line
options to change sorting or display modes, which disrupted continuous
monitoring and reduced productivity during performance investigations.

Adds real-time interactive controls through keyboard input:
1) Add interactive menu system with visual prompts
2) Support dynamic sorting changes without restarting
3) Enable toggle of memory verbose mode with 'M' key

The interactive mode transforms delaytop from a static monitoring tool
into a dynamic investigation platform, allowing users to adapt the view in
real-time based on observed performance patterns.

Link: https://lkml.kernel.org/r/20250907001338580EURha20BxWFmBSrUpS8D1@zte.com.cn
Signed-off-by: Fan Yu <fan.yu9@zte.com.cn>
Reviewed-by: xu xin <xu.xin16@zte.com.cn>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/tools/accounting/delaytop.c b/tools/accounting/delaytop.c
index 30dc95fb531aa8a96d8166a3c29090833bc50a5a..7bd1a1eeb354d22266ad12bd67ec61571f6ce645 100644 (file)
--- a/tools/accounting/delaytop.c
+++ b/tools/accounting/delaytop.c
@@ -73,8 +73,8 @@
 #define PSI_LINE_FORMAT "%-12s %6.1f%%/%6.1f%%/%6.1f%%/%8llu(ms)\n"
 #define DELAY_FMT_DEFAULT "%8.2f %8.2f %8.2f %8.2f\n"
 #define DELAY_FMT_MEMVERBOSE "%8.2f %8.2f %8.2f %8.2f %8.2f %8.2f\n"
-#define SORT_FIELD(name, modes) \
-       {#name, \
+#define SORT_FIELD(name, cmd, modes) \
+       {#name, #cmd, \
        offsetof(struct task_info, name##_delay_total), \
        offsetof(struct task_info, name##_count), \
        modes}
@@ -140,6 +140,7 @@ struct container_stats {
 /* Delay field structure */
 struct field_desc {
        const char *name;       /* Field name for cmdline argument */
+       const char *cmd_char;   /* Interactive command */
        unsigned long total_offset; /* Offset of total delay in task_info */
        unsigned long count_offset; /* Offset of count in task_info */
        size_t supported_modes; /* Supported display modes */
@@ -165,17 +166,18 @@ static int task_count;
 static int running = 1;
 static struct container_stats container_stats;
 static const struct field_desc sort_fields[] = {
-       SORT_FIELD(cpu,         MODE_DEFAULT),
-       SORT_FIELD(blkio,       MODE_DEFAULT),
-       SORT_FIELD(irq,         MODE_DEFAULT),
-       SORT_FIELD(mem,         MODE_DEFAULT | MODE_MEMVERBOSE),
-       SORT_FIELD(swapin,      MODE_MEMVERBOSE),
-       SORT_FIELD(freepages,   MODE_MEMVERBOSE),
-       SORT_FIELD(thrashing,   MODE_MEMVERBOSE),
-       SORT_FIELD(compact,     MODE_MEMVERBOSE),
-       SORT_FIELD(wpcopy,      MODE_MEMVERBOSE),
+       SORT_FIELD(cpu,         c,      MODE_DEFAULT),
+       SORT_FIELD(blkio,       i,      MODE_DEFAULT),
+       SORT_FIELD(irq,         q,      MODE_DEFAULT),
+       SORT_FIELD(mem,         m,      MODE_DEFAULT | MODE_MEMVERBOSE),
+       SORT_FIELD(swapin,      s,      MODE_MEMVERBOSE),
+       SORT_FIELD(freepages,   r,      MODE_MEMVERBOSE),
+       SORT_FIELD(thrashing,   t,      MODE_MEMVERBOSE),
+       SORT_FIELD(compact,     p,      MODE_MEMVERBOSE),
+       SORT_FIELD(wpcopy,      w,      MODE_MEMVERBOSE),
        END_FIELD
 };
+static int sort_selected;
 
 /* Netlink socket variables */
 static int nl_sd = -1;
@@ -197,6 +199,19 @@ static void disable_raw_mode(void)
        tcsetattr(STDIN_FILENO, TCSAFLUSH, &orig_termios);
 }
 
+/* Find field descriptor by command line */
+static const struct field_desc *get_field_by_cmd_char(char ch)
+{
+       const struct field_desc *field;
+
+       for (field = sort_fields; field->name != NULL; field++) {
+               if (field->cmd_char[0] == ch)
+                       return field;
+       }
+
+       return NULL;
+}
+
 /* Find field descriptor by name with string comparison */
 static const struct field_desc *get_field_by_name(const char *name)
 {
@@ -870,6 +885,18 @@ static void display_results(void)
                        container_stats.nr_stopped, container_stats.nr_uninterruptible,
                        container_stats.nr_io_wait);
        }
+
+       /* Interacive command */
+       suc &= BOOL_FPRINT(out, "[o]sort [M]memverbose [q]quit\n");
+       if (sort_selected) {
+               if (cfg.display_mode == MODE_MEMVERBOSE)
+                       suc &= BOOL_FPRINT(out,
+                               "sort selection: [m]MEM [r]RCL [t]THR [p]CMP [w]WP\n");
+               else
+                       suc &= BOOL_FPRINT(out,
+                               "sort selection: [c]CPU [i]IO [m]MEM [q]IRQ\n");
+       }
+
        /* Task delay output */
        suc &= BOOL_FPRINT(out, "Top %d processes (sorted by %s delay):\n",
                        cfg.max_processes, get_name_by_field(cfg.sort_field));
@@ -919,11 +946,78 @@ static void display_results(void)
                perror("Error writing to output");
 }
 
+/* Check for keyboard input with timeout based on cfg.delay */
+static char check_for_keypress(void)
+{
+       struct timeval tv = {cfg.delay, 0};
+       fd_set readfds;
+       char ch = 0;
+
+       FD_ZERO(&readfds);
+       FD_SET(STDIN_FILENO, &readfds);
+       int r = select(STDIN_FILENO + 1, &readfds, NULL, NULL, &tv);
+
+       if (r > 0 && FD_ISSET(STDIN_FILENO, &readfds)) {
+               read(STDIN_FILENO, &ch, 1);
+               return ch;
+       }
+
+       return 0;
+}
+
+#define MAX_MODE_SIZE 2
+static void toggle_display_mode(void)
+{
+       static const size_t modes[MAX_MODE_SIZE] = {MODE_DEFAULT, MODE_MEMVERBOSE};
+       static size_t cur_index;
+
+       cur_index = (cur_index + 1) % MAX_MODE_SIZE;
+       cfg.display_mode = modes[cur_index];
+}
+
+/* Handle keyboard input: sorting selection, mode toggle, or quit */
+static void handle_keypress(char ch, int *running)
+{
+       const struct field_desc *field;
+
+       /* Change sort field */
+       if (sort_selected) {
+               field = get_field_by_cmd_char(ch);
+               if (field && (field->supported_modes & cfg.display_mode))
+                       cfg.sort_field = field;
+
+               sort_selected = 0;
+       /* Handle mode changes or quit */
+       } else {
+               switch (ch) {
+               case 'o':
+                       sort_selected = 1;
+                       break;
+               case 'M':
+                       toggle_display_mode();
+                       for (field = sort_fields; field->name != NULL; field++) {
+                               if (field->supported_modes & cfg.display_mode) {
+                                       cfg.sort_field = field;
+                                       break;
+                               }
+                       }
+                       break;
+               case 'q':
+               case 'Q':
+                       *running = 0;
+                       break;
+               default:
+                       break;
+               }
+       }
+}
+
 /* Main function */
 int main(int argc, char **argv)
 {
+       const struct field_desc *field;
        int iterations = 0;
-       int use_q_quit = 0;
+       char keypress;
 
        /* Parse command line arguments */
        parse_args(argc, argv);
@@ -943,20 +1037,20 @@ int main(int argc, char **argv)
                exit(1);
        }
 
-       if (!cfg.output_one_time) {
-               use_q_quit = 1;
-               enable_raw_mode();
-               printf("Press 'q' to quit.\n");
-               fflush(stdout);
-       }
+       /* Set terminal to non-canonical mode for interaction */
+       enable_raw_mode();
 
        /* Main loop */
        while (running) {
-               /* Exit when sort field do not match display mode */
+               /* Auto-switch sort field when not matching display mode */
                if (!(cfg.sort_field->supported_modes & cfg.display_mode)) {
-                       fprintf(stderr, "Sort field not supported in this mode\n");
-                       display_available_fields(cfg.display_mode);
-                       break;
+                       for (field = sort_fields; field->name != NULL; field++) {
+                               if (field->supported_modes & cfg.display_mode) {
+                                       cfg.sort_field = field;
+                                       printf("Auto-switched sort field to: %s\n", field->name);
+                                       break;
+                               }
+                       }
                }
 
                /* Read PSI statistics */
@@ -983,32 +1077,14 @@ int main(int argc, char **argv)
                if (cfg.output_one_time)
                        break;
 
-               /* Check for 'q' key to quit */
-               if (use_q_quit) {
-                       struct timeval tv = {cfg.delay, 0};
-                       fd_set readfds;
-
-                       FD_ZERO(&readfds);
-                       FD_SET(STDIN_FILENO, &readfds);
-                       int r = select(STDIN_FILENO+1, &readfds, NULL, NULL, &tv);
-
-                       if (r > 0 && FD_ISSET(STDIN_FILENO, &readfds)) {
-                               char ch = 0;
-
-                               read(STDIN_FILENO, &ch, 1);
-                               if (ch == 'q' || ch == 'Q') {
-                                       running = 0;
-                                       break;
-                               }
-                       }
-               } else {
-                       sleep(cfg.delay);
-               }
+               /* Keypress for interactive usage */
+               keypress = check_for_keypress();
+               if (keypress)
+                       handle_keypress(keypress, &running);
        }
 
        /* Restore terminal mode */
-       if (use_q_quit)
-               disable_raw_mode();
+       disable_raw_mode();
 
        /* Cleanup */
        close(nl_sd);