update README with new workings and add license header everywhere

Author: jrudolph

AttachOnce.java

@@ -1,3 +1,23 @@
+/*
+ *   libperfmap: a JVM agent to create perf-<pid>.map files for consumption
+ *               with linux perf-tools
+ *   Copyright (C) 2013 Johannes Rudolph<[email protected]>
+ *
+ *   This program is free software; you can redistribute it and/or modify
+ *   it under the terms of the GNU General Public License as published by
+ *   the Free Software Foundation; either version 2 of the License, or
+ *   (at your option) any later version.
+ *
+ *   This program is distributed in the hope that it will be useful,
+ *   but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *   GNU General Public License for more details.
+ *
+ *   You should have received a copy of the GNU General Public License along
+ *   with this program; if not, write to the Free Software Foundation, Inc.,
+ *   51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
 package net.virtualvoid.perf;
 
 import java.io.File;

README.md

@@ -1,4 +1,4 @@
-A java agent to generate /tmp/perf-<pid>.map files for JITted methods for use with `perf`
+A java agent to generate `/tmp/perf-<pid>.map` files for JITted methods for use with `perf`.
 
 ## Build
 
@@ -7,16 +7,15 @@ A java agent to generate /tmp/perf-<pid>.map files for JITted methods for use wi
 
 ## Use
 
-Add `-agentpath:<dir>/libperfmap.so` to the java command line.
+Use `./perf-java <pid> <options>` to create a `perf-<pid>.map` file for the current state of the JVM and
+run `perf top -p <pid>` for this process afterwards. `perf-java` expects `libperfmap.so` in the current directory.
+
+Over time the JVM will JIT compile more methods and the `perf-<pid>.map` file will become stale. You need to
+rerun `perf-java` to generate a new and current map.
 
 Note: If `perf top` still doesn't show any detailled info it's probably because of a permission problem. A common solution is
 to run the java program as a regular user with the agent enabled and then run a `chown root /tmp/perf-<pid>.map` to make
-the file accessible for the root user. Then run `perf top` as root. You could use the following script to do that:
-
-```sh
-sudo chown root /tmp/perf-$1.map
-sudo perf top
-```
+the file accessible for the root user. Then run `perf top` as root. The `perf-java` script tries to do that.
 
 ## Disclaimer
 

perf-map-agent.c

@@ -17,6 +17,7 @@
  *   with this program; if not, write to the Free Software Foundation, Inc.,
  *   51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  */
+
 #include <stdio.h>
 
 #include <sys/types.h>

perf-map-file.c

@@ -1,3 +1,23 @@
+/*
+ *   libperfmap: a JVM agent to create perf-<pid>.map files for consumption
+ *               with linux perf-tools
+ *   Copyright (C) 2013 Johannes Rudolph<[email protected]>
+ *
+ *   This program is free software; you can redistribute it and/or modify
+ *   it under the terms of the GNU General Public License as published by
+ *   the Free Software Foundation; either version 2 of the License, or
+ *   (at your option) any later version.
+ *
+ *   This program is distributed in the hope that it will be useful,
+ *   but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *   GNU General Public License for more details.
+ *
+ *   You should have received a copy of the GNU General Public License along
+ *   with this program; if not, write to the Free Software Foundation, Inc.,
+ *   51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
 #include <sys/types.h>
 #include <stdio.h>
 

perf-map-file.h

@@ -1,3 +1,23 @@
+/*
+ *   libperfmap: a JVM agent to create perf-<pid>.map files for consumption
+ *               with linux perf-tools
+ *   Copyright (C) 2013 Johannes Rudolph<[email protected]>
+ *
+ *   This program is free software; you can redistribute it and/or modify
+ *   it under the terms of the GNU General Public License as published by
+ *   the Free Software Foundation; either version 2 of the License, or
+ *   (at your option) any later version.
+ *
+ *   This program is distributed in the hope that it will be useful,
+ *   but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *   GNU General Public License for more details.
+ *
+ *   You should have received a copy of the GNU General Public License along
+ *   with this program; if not, write to the Free Software Foundation, Inc.,
+ *   51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
 FILE *perf_map_open(pid_t pid);
 void perf_map_write_entry(FILE *method_file, const void* code_addr, unsigned int code_size, const char* entry);