Networking setup

1 files changed, 22 insertions, 0 deletions

diff --git a/src/DEVELOPMENT b/src/DEVELOPMENT
index f3381fb..a40e2bb 100644
--- a/src/DEVELOPMENT
+++ b/src/DEVELOPMENT
@@ -10,6 +10,28 @@ Architecture
   for missing bits.
 
 
+Problems
+========
+ - When streaming at high speed (~ 16 data streams; 600 Mbit & 600 kpck each), the data streams quickly get
+ desynchronized (but all packets are delivered).
+    * It is unclear if problem is on the receiver side (no overloaded CPU cores) or de-synchronization is first
+    appear on the simmulation sender. The test with real hardware is required.
+    * For border case scenarios, increasing number of buffers from 2 to 10-20 helps. But at full speed, even 1000s
+    buffers are not enough. Packets counts are quickly going appart.
+    * Further increase of packet buffer provided to 'recvmmsg' does not help (even if blocking is enforced until 
+    all packets are received)
+    * At the speed specified above, the system works also without libvma.
+    * Actually, with libvma a larger buffer is required. In the beginning the performance of libvma is gradually 
+    speeding up (that was always like that). And during this period a significant desynchronization happens. To
+    compensate it, we need about 400 buffers with libvma as compared to only 10 required if standard Linux 
+    networking is utilized.
+ - Can we pre-heat to avoid this speeding-up problem? Or it will be also not a problem with hardware?
+ - Communication breaks with small MTU sizes (bellow 1500), but this is probably not important (Packets are 
+ delivered but with extreme latencies. Probably some tunning of network stack is required).
+ - Technically, everything should work if we start UFO server when data is already streamed. However, the first
+ dataset could be any. Therefore, the check fails as the data is shifted by a random number of datasets.
+
+
 Questions
 =========
  - Can we pre-allocate several UFO buffers for forth-comming events. Currently, we need to buffer out-of-order