Merge branch 'collectd-5.7' into collectd-5.8

[collectd.git] / docs / BUILD.dpdkstat.md

diff --git a/docs/BUILD.dpdkstat.md b/docs/BUILD.dpdkstat.md
index fe9f0e6..457fc0f 100644 (file)
--- a/docs/BUILD.dpdkstat.md
+++ b/docs/BUILD.dpdkstat.md
@@ -1,7 +1,17 @@
 # The dpdkstat plugin
 
+This plugin is optional and only has a specific use case: monitoring DPDK applications
+that don't expose stats in any other way than the DPDK xstats API.
+
 **Data Plane Development Kit** (DPDK) is a set of drivers and libraries for fast
-packet processing.
+packet processing. Please note that this plugin is a polling based plugin rather
+than an events based plugin (using it will drive up core utilization on a system).
+
+**PLEASE DO NOT USE THIS PLUGIN FOR OVS-DPDK**. dpdkstat is really for DPDK
+applications that have no other way of exposing stats. For OVS or OVS-with-DPDK the
+Open vSwitch plugins available in collectd 5.8.0 should be used for
+collecting stats and events. In addition the OVS plugin is events based rather
+than polling based and will have a smaller footprint on the system.
 
 ## Summary
 
@@ -208,6 +218,12 @@ See also: http://dpdk.org/doc/guides/prog_guide/multi_proc_support.html
  *  The same PCI device configuration should be passed to the primary process as
     the secondary process uses the same port indexes as the primary.
  *  A blacklist / whitelist of NICs isn't supported yet.
+ *  Plugin initialization time depends on read interval. It requires 5 read
+    cycles to set up internal buffers and states. During that time no statistics
+    are submitted.
+ *  If number of DPDK ports is increased while plugin is running, internal
+    buffers are resized. That requires 3 read cycles and no port statistics
+    are submitted in that time.
 
 ## License