3-Jul-1994
======== breaf usage of novad v1.10 ========

    The modified part is only argument of "novad". You can get a breaf 
usage by typing like below.
---------------------------------
prompt% novad <return>

  NOVA Buffer Manager version 1.10  2-Jul-1994 written by M.Nomachi, Y.Takeuchi
  usage: novad [options] name [options] 

       -b #    buffer size in K-byte          (default 16)
       -B #    buffer size in byte
       -n #    number of buffers              (default  8)
       -p #    max number of client processes (default 20)
       -v #    max free buffer length         (default  0)
       -V #    max free buffer length in byte                
                 <= 0: fixed length buffer                
                  > 0: variable length buffer             

---------------------------------
    Here "-v", "-V" and "-B" are the new options. You can use v1.10 like 
v1.08, when "-v" and "-V" are omitted. (v1.10 is upper compatible with v1.08)


======== examples of novad v1.10's arguments ========

1.  buffer size    = 4500 bytes (fixed) 
    # of buffers   = 100
    # of processes = 20
    total shared memory for buffers = 100 * 4500 bytes (fixed)

	novad -B 4500 -n 100 -p 20 /tmp/nova


2.  buffer size    = (from 1 byte?) up to  5 Kbytes (variable) 
    # of buffers   = 100
    # of processes = 10
    total shared memory for buffers = 300 Kbytes

	novad -b 3 -n 100 -p 10 -v 5 /tmp/nova


3.  buffer size    = (from 1 byte?) up to  6 Mbytes (variable) 
    # of buffers   = 60
    # of processes = 10
    total shared memory for buffers = 30 Mbytes

	novad -b 512 -n 60 -p 10 -v 6144 /tmp/nova


======== behavior of novad v1.10 ========

    Now we think the case of example3 and 1 producer process and 2 consumer 
processes exists.
		novad -b 512 -n 60 -p 10 -v 6144 /tmp/nova

		free_buffer =====> producer ==> consumer1 ==> consumer2
# of buffer    	 1       58   1	     0	          0		0
buffer size    	24Mbytes  0   6M



When producer calls "nova_get()", The process gets a 6Mbytes free buffer.

		free_buffer =====> producer ==> consumer1 ==> consumer2
# of buffer    	 1  58        0	     1	          0		0
buffer size    	24M  0	             6M



When producer uses 1Mbyte of the buffer, producer sets "length=1024*1024" 
then calls "nova_put(...,length)". The buffer length is settled at this time.
The remainng buffer area are returned to the free buffer queue, and next 
free buffer is prepared for producer.

		free_buffer =====> producer ==> consumer1 ==> consumer2
# of buffer    	 1  57        1	     0            1		0
buffer size    	23M  0        6M   	          1M

		free_buffer =====> producer ==> consumer1 ==> consumer2
# of buffer    	 1  57        1	     0            0		1
buffer size    	23M  0        6M	                        1M

		free_buffer =====> producer ==> consumer1 ==> consumer2
# of buffer    	 1   1	57    1	     0            0		0
buffer size    	 1M 23M	 0    6M