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User Manual
Rev 6.9.1
VMA Configuration Parameter
Description and Examples
VMA_RX_BYTES_MIN
The minimum value in bytes used per socket by the VMA
when applications call to setsockopt(SO_RCVBUF).
If the application tries to set a smaller value than configured
in VMA_RX_BYTES_MIN, VMA forces this minimum limit
value on the socket.
VMA offloaded sockets receive the maximum amount of
ready bytes. If the application does not drain sockets and the
byte limit is reached, newly received datagrams are dropped.
The application's socket usage of current, max,dropped bytes
and packet counters, can be monitored using vma_stats.
Default: 65536.
VMA_RX_POLL
The number of times to unsuccessfully poll an Rx for VMA
packets before going to sleep.
Range:
-1, 0 … 100,000,000
Default: 100,000
This value can be reduced to lower the load on the CPU.
However, the price paid for this is that the Rx latency is
expected to increase.
Recommended values:
 10000 – when CPU usage is not critical and Rx path
latency is critical.
 0 – when CPU usage is critical and Rx path latency is not
critical.
 -1 – causes infinite polling.
Once the VMA has gone to sleep, if it is in blocked mode, it
waits for an interrupt; if it is in non-blocked mode, it returns 1.
This Rx polling is performed when the application is working
with direct blocked calls to read(), recv(),
recvfrom(), and recvmsg().
When the Rx path has successful poll hits, the latency
improves dramatically. However, this causes increased CPU
utilization. For more information, see Debugging,
Troubleshooting, and Monitoring (on page 37).
VMA_RX_POLL_INIT
VMA maps all UDP sockets as potential Offloaded-capable.
Only after ADD_MEMBERSHIP is set, the offload starts
working and the CQ polling starts VMA.
This parameter controls the polling count during this
transition phase where the socket is a UDP unicast socket and
no multicast addresses were added to it.
Once the first ADD_MEMBERSHIP is called, the
VMA_RX_POLL (above) takes effect.
Value range is similar to the VMA_RX_POLL (above).
Default: 0
VMA_RX_UDP_POLL_OS_RATI
O
Defines the ratio between VMA CQ poll and OS FD poll.
This will result in a single poll of the not-offloaded sockets
every
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