PID_MAX_DEFAULT

A few things have changed since PID_MAX_DEFAULT was set to 0x8000. It's now adjustable via the /proc/sys/kernel/pid_max file. An app, /bin/ps, now reads this file to determine column width for PID, PPID, PGID, SESS, LWP, and so on.

The common-case Linux box is best served by a value that keeps /bin/ps PID columns narrow, allowing for more space elsewhere. The following patch gives 4-digit PID values as a default.

diff -Naurd old/include/linux/threads.h new/include/linux/threads.h
@@ -25,7 +25,7 @@
 /*
  * This controls the default maximum pid allocated to a process
  */
-#define PID_MAX_DEFAULT 0x8000
+#define PID_MAX_DEFAULT 10000
 
 /*
  * A maximum of 4 million PIDs should be enough for a while: