Documentation / comments

README.md

@@ -15,3 +15,21 @@ FabricMon's web interface, based on the d3.js graph library, and displayed as
 an SVG force graph.
 
 This project is a work in progress, in the early stages of development.
+
+Building FabricMon
+------------------
+To build FabricMon, you will require the following development libraries
+(Debian package names shown):
+
+* libibmad-dev
+* libibumad-dev
+* libibnetdisc-dev
+
+The corresponding runtime libraries will be required on the target system
+unless you build the FabricMon binary with static linking.
+
+InfiniBand Counters
+-------------------
+Note that counters that represent data (e.g. PortXmitData and PortRcvData) are
+divided by four (lanes). See https://community.mellanox.com/docs/DOC-2572 for
+more information.

main.go

@@ -184,6 +184,10 @@ func iterateSwitches(f *Fabric, nnMap *NodeNameMap, conf influxdbConf) {
 					capMask := nativeEndian.Uint16(buf[2:4])
 					fmt.Printf("Cap Mask: %#02x\n", ntohs(capMask))
 
+					// Note: In PortCounters, PortCountersExtended, PortXmitDataSL, and
+					// PortRcvDataSL, components that represent Data (e.g. PortXmitData and
+					// PortRcvData) indicate octets divided by 4 rather than just octets.
+
 					// Fetch standard (32 bit, some 16 bit) counters
 					pmaBuf = C.pma_query_via(unsafe.Pointer(&buf), &portid, C.int(portNum), PMA_TIMEOUT, C.IB_GSI_PORT_COUNTERS, f.ibmadPort)
 
@@ -215,9 +219,6 @@ func iterateSwitches(f *Fabric, nnMap *NodeNameMap, conf influxdbConf) {
 					pmaBuf = C.pma_query_via(unsafe.Pointer(&buf), &portid, C.int(portNum), PMA_TIMEOUT, C.IB_GSI_PORT_COUNTERS_EXT, f.ibmadPort)
 
 					if pmaBuf != nil {
-						// Note: In PortCounters, PortCountersExtended, PortXmitDataSL, and
-						// PortRcvDataSL, components that represent Data (e.g. PortXmitData and
-						// PortRcvData) indicate octets divided by 4 rather than just octets.
 						for counter, displayName := range extCounterMap {
 							tags["counter"] = displayName
 							fields["value"] = getCounterUint32(pmaBuf, counter)