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Directory /proc/sys/ps4/state
18 ParaStation5 Administrator's Guide
The p4sock.ko module inserts a number of entries within the /proc filesystem. All ParaStation5 entries are
located within the subdirectory /proc/sys/ps4. Three different subdirectories, listed below, are available.
To read a value, e.g. just type
# cat /proc/sys/ps4/state/connections
to get the number of currently open connections. To modify a value, for e.g. type
# echo 10 > /proc/sys/ps4/state/ResendTimeout
to set the new value for ResendTimeout.
5.2.1. Directory /proc/sys/ps4/state
Within this state directory, various entries showing protocol counters. All these entries, except polling,
are read only!
• HZ: reads the number of timer interrupts per second for this kernel ("jiffies").
A jiffy is the base unit for system timers, used by the Linux kernel. So all timeouts
within the kernel are based on this timer resolution. On kernels with version 2.4, this
it typically 100Hz (= 10ms). But there are kernel versions available, e.g. for newer
SuSE Linux versions, which include patches to change this to a much higher value!
• connections: reads the current number of open connections.
• polling: returns the current value for the polling flag: 0 = never poll, 1 = poll if otherwise idle (number
of runable processes < number of CPUs), 2 = always poll. Writing this value will immediately change
the polling strategy.
• recv_net_ack: number of received ACKs.
• recv_net_ctrl: number of received control packets (ACK, NACK, SYN, SYNACK, ...).
• recv_net_data: number of received data packets.
• recv_net_nack: number of received NACKs.
• recv_user: number of packets delivered to application buffers.
• send_net_ack: number of sent ACKs.
• send_net_ctrl: number of sent control packets.
• send_net_data: number of sent data packets.
• send_net_nack: number of sent NACKs.
• send_user: number of packets sent by the application.
• sockets: number of open sockets connecting to the ParaStation5 protocol module.
• timer_ack: number of expired delayed ACK timers.
• timer_resend: number of expired resend timers.
5.2.2. Directory /proc/sys/ps4/ether
Within this directory, all Ethernet related parameters for the ParaStation5 p4sock protocol are grouped. All
these entries can be read and written, newly written values will be used immediately.
• AckDelay: maximum delay in "jiffies" for ACK messages. If no message is sent within this time frame,
where an ACK for already received packets can be "hooked up", a single ACK message will generated.
Must be less then ResendTimeout.