HP 9000 Installation And Configuration Manual page 81

zcom_mem_size = <card> * <rate> * <time> * (<length> + 200) * 1.5
<rate> = (<bps_rate> * <num_ports> * <duplex>) / <msg_len>
rate = (((57.6 * 103 / 8) * 5) * 1) / 100 = 576
Appendix B
An appropriate value for zcom_mem_size can be estimated using the
following algorithm:
where:
<card>
<rate>
<time>
<length>
200
1.5
The rate value is calculated as follows:
where:
<bps_rate>
<num_ports>
<duplex>
<msg_len>
For example, for a system with 5 ports (at 57.6 Kbits per second per port)
running half duplex with a message length of 100 bytes per message:
number of mux cards on the system
maximum number of messages per
second per mux card (Refer to the
calculation shown below.)
average turn-around time for one
message (including transmission
time). This also depends on the SPU
processing power. For most systems, 5
seconds should be adequate.
average message length.
memory overhead per message (in
bytes)
scaling factor to allow for usable gaps
in the buffer pool
rate of port in bits per second divided
by 8
number of ports in use.
half duplex = 1; full duplex = 2
average number of bytes per message
Tuning and Sizing
ZCOM_MEM_SIZE
81