perf(userland): replace sys_yield with sleep for WAY better idle efficiency

src/userland/cli/bsh.c

@@ -1438,7 +1438,7 @@ static int read_line(char *out, int max_len, const char *prompt_tmpl) {
         int got = sys_tty_read_in(&ch, 1);
         if (got <= 0) {
             // Throttle idle input polling to avoid pegging the CPU at 100%
-            sleep(1);
+            sleep(50);
             continue;
         }
 

src/userland/games/2048.c

@@ -496,7 +496,7 @@ int main(int argc, char **argv) {
                 ui_mark_dirty(win, 0, 0, WINDOW_W, WINDOW_H);
             }
         } else {
-            sys_yield();
+            sys_system(SYSTEM_CMD_SLEEP, 10, 0, 0, 0);
         }
     }
 

src/userland/gui/boredword.c

@@ -1988,7 +1988,7 @@ int main(int argc, char **argv) {
             ui_mark_dirty(win, 0, 0, win_w, win_h);
             needs_repaint = 0;
         } else {
-            sys_yield();
+            sys_system(SYSTEM_CMD_SLEEP, 16, 0, 0, 0);
         }
     }
     return 0;

src/userland/gui/keylog.c

@@ -54,7 +54,7 @@ int main(void) {
             draw(win);
             ui_mark_dirty(win, 0, 0, WINDOW_W, WINDOW_H);
         } else {
-            sys_yield();
+            sys_system(SYSTEM_CMD_SLEEP, 10, 0, 0, 0);
         }
     }
 

src/userland/libc/posix_io.c

@@ -158,7 +158,7 @@ static int _b_pipe_read(fd_handle_t *h, void *buf, size_t count) {
                 }
                 break;
             }
-            sys_yield();
+            sleep(1);
             continue;
         }
 
@@ -193,7 +193,7 @@ static int _b_pipe_write(fd_handle_t *h, const void *buf, size_t count) {
                 }
                 break;
             }
-            sys_yield();
+            sleep(1);
             continue;
         }
 

src/userland/libc/posix_process.c

@@ -3,6 +3,7 @@
 
 #include "errno.h"
 #include "stdio.h"
+#include "stdlib.h"
 #include "string.h"
 #include "sys/types.h"
 #include "sys/wait.h"
@@ -219,6 +220,6 @@ __attribute__((weak)) pid_t waitpid(pid_t pid, int *status, int options) {
             errno = ECHILD;
             return -1;
         }
-        sys_yield();
+        sleep(1);
     }
 }

src/userland/net/telnet.c

@@ -363,7 +363,7 @@ int main(int argc, char **argv) {
                 connected = 0;
                 break;
             }
-            sys_yield();
+            sys_system(SYSTEM_CMD_SLEEP, 10, 0, 0, 0);
             continue;
         }