[sajia@211 temp]$ java -cp .:$JAVA_HOME/lib/sa-jdi.jar DirectMemorySize     
Usage: java directMemorySize [option] <pid>
                (to connect to a live java process)
   or java directMemorySize [option] <executable> <core>
                (to connect to a core file)
   or java directMemorySize [option] [server_id@]<remote server IP or hostname>
                (to connect to a remote debug server)

where option must be one of:
    -e  to print the actual size malloc'd
    -v  to print verbose info of every live DirectByteBuffer allocated from Java
    -h | -help  to print this help message
[sajia@211 temp]$ java -cp .:$JAVA_HOME/lib/sa-jdi.jar DirectMemorySize `pgrep -u sajia java`
Attaching to process ID 7381, please wait...
Debugger attached successfully.
Server compiler detected.
JVM version is 20.5-b03
NIO direct memory: (in bytes)
  reserved size = 0.000003 MB (3 bytes)
  max size      = 7152.000000 MB (7499415552 bytes)
[sajia@211 temp]$ java -cp .:$JAVA_HOME/lib/sa-jdi.jar DirectMemorySize -e `pgrep -u sajia java`
Attaching to process ID 7381, please wait...
Debugger attached successfully.
Server compiler detected.
JVM version is 20.5-b03
NIO direct memory: (in bytes)
  reserved size = 0.000003 MB (3 bytes)
  max size      = 7152.000000 MB (7499415552 bytes)
Finding object size using Printezis bits and skipping over...
Finding object size using Printezis bits and skipping over...
NIO direct memory malloc'd size: 0.007815 MB (8195 bytes)
[sajia@211 temp]$ time java -cp .:$JAVA_HOME/lib/sa-jdi.jar DirectMemorySize `pgrep -u sajia java`      
Attaching to process ID 7381, please wait...
Debugger attached successfully.
Server compiler detected.
JVM version is 20.5-b03
NIO direct memory: (in bytes)
  reserved size = 0.000003 MB (3 bytes)
  max size      = 7152.000000 MB (7499415552 bytes)

real    0m0.401s
user    0m0.503s
sys     0m0.057s
[sajia@211 temp]$ time java -cp .:$JAVA_HOME/lib/sa-jdi.jar DirectMemorySize -e `pgrep -u sajia java`
Attaching to process ID 7381, please wait...
Debugger attached successfully.
Server compiler detected.
JVM version is 20.5-b03
NIO direct memory: (in bytes)
  reserved size = 0.000003 MB (3 bytes)
  max size      = 7152.000000 MB (7499415552 bytes)
Finding object size using Printezis bits and skipping over...
Finding object size using Printezis bits and skipping over...
NIO direct memory malloc'd size: 0.007815 MB (8195 bytes)

real    0m4.822s
user    0m2.095s
sys     0m3.216s
[sajia@211 temp]$ time java -cp .:$JAVA_HOME/lib/sa-jdi.jar DirectMemorySize -e -v `pgrep -u sajia java`
Attaching to process ID 7381, please wait...
Debugger attached successfully.
Server compiler detected.
JVM version is 20.5-b03
NIO direct memory: (in bytes)
  reserved size = 0.000003 MB (3 bytes)
  max size      = 7152.000000 MB (7499415552 bytes)
Currently allocated direct buffers:
  0x00002aaab021df10: capacity = 0.000001 MB (1 bytes), mallocSize = 0.003907 MB (4097 bytes)
  0x00002aaab0843310: capacity = 0.000002 MB (2 bytes), mallocSize = 0.003908 MB (4098 bytes)
Finding object size using Printezis bits and skipping over...
Finding object size using Printezis bits and skipping over...
NIO direct memory malloc'd size: 0.007815 MB (8195 bytes)

real    0m5.097s
user    0m2.164s
sys     0m3.426s
[sajia@211 temp]$