issue: 954841 Add VMA_SPEC "latency" to README.txt file

VMA_SPEC is a predefined specification profile for latency.
Optimized for use cases that are keen on latency. i.e. Ping-Pong tests.

Signed-off-by: Daniel Libenson <[email protected]>

README.txt

@@ -249,6 +249,33 @@ the process loaded with VMA. This can help in running multiple instances of VMA
 each with it's own log file name.
 Example:  VMA_LOG_FILE=/tmp/vma_log.txt
 
+VMA_SPEC
+VMA predefined specification profile for latency.
+Optimized for use cases that are keen on latency. i.e. Ping-Pong tests.
+
+Latency SPEC changes the following default configuration
+ VMA_TX_WRE = 256                         (default: 3000)
+ VMA_TX_WRE_BATCHING = 4                  (default: 64)
+ VMA_RX_WRE = 256                         (default: 16000)
+ VMA_RX_WRE_BATCHING = 4                  (default: 64)
+ VMA_RX_POLL = -1                         (default: 100000)
+ VMA_RX_PREFETCH_BYTES_BEFORE_POLL = 256  (default: 0)
+ VMA_GRO_STREAMS_MAX = 0                  (default: 32)
+ VMA_SELECT_POLL = -1                     (default: 100000)
+ VMA_SELECT_POLL_OS_FORCE = Enable        (default: Disabled)
+ VMA_SELECT_POLL_OS_RATIO = 1             (default: 10)
+ VMA_SELECT_SKIP_OS = 1                   (default: 4)
+ VMA_PROGRESS_ENGINE_INTERVAL = 100       (default: 10)
+ VMA_CQ_MODERATION_ENABLE = Disable       (default: Enabled)
+ VMA_CQ_AIM_MAX_COUNT = 128               (default: 560)
+ VMA_CQ_AIM_INTERVAL_MSEC = Disable       (default: 250)
+ VMA_CQ_KEEP_QP_FULL = Disable            (default: Enable)
+ VMA_AVOID_SYS_CALLS_ON_TCP_FD = Enable   (default: Disable)
+ VMA_INTERNAL_THREAD_AFFINITY = 0         (default: -1)
+ VMA_THREAD_MODE = Single                 (default: Multi spin lock)
+ VMA_MEM_ALLOC_TYPE = 2                   (default: 1 (Contig Pages))
+Example: VMA_SPEC=latency
+
 VMA_STATS_FILE
 Redirect socket statistics to a specific user defined file.
 VMA will dump each socket's statistics into a file when closing the socket.