Ptolemy EVM Simulation

1
Ptolemy EVM Simulation

• Simple EVM option
• Simple EVM which is connected to last leg of
  switch on RU side (see fig on next slide) ? the
  number of BUs is one higher than the number of
  RUs in this configuration.
• An external Ethernet network (RCN) to broadcast
  event IDs to Readout units. An extra port
  introduced in each RU for RCN network.
• Trigger rate mean is 12.5 kHz by default
• Poisson by default
• Gaussian with cut-off also possible
• Event Fragments are 16 ? 16 kB LogNormal by
  default
• Other standard RU options available too
• Each BU has 8 filter nodes by default
• Filter farm default event processing time 40 ? 4
  ms per event

2
RCN Over Myrinet
3
EVM Messages

• BM Messages
• CMSAllocate message is for making new event ID
  requests to BM
• CMSClear message is for sending clear request to
  BM
• CMSConfirm message is for assigning event IDs to
  BU.
• RM Messages
• CMSRCN message is for distributing event IDs to
  all read out units.

4
How it works

• In this configuration messages are packed before
  sending them to the network. The RM puts each
  arriving trigger in its trigger buffer and does
  not broadcast it to RUs immediately. This trigger
  buffer by default holds 10 triggers in it in this
  configuration. When this buffer becomes full, RM
  sends an RCN message containing the 10 event IDs
  to all readout units.
• Each builder unit has 256 resources by default.
  On startup each builder unit by default makes 256
  requests to BM for 256 event IDs, one at a time.
  BM fulfills these requests in batches, because
  the RM makes events available in batches and the
  BM is participating in the RU-side barrel
  shifting. The BM puts event requests into a FIFO
  and serves event IDs accordingly. Due to
  randomization in the Myrinet code the FIFO is
  unordered, such that BUs typically receive one
  event ID at a time.

5
Active Events

• The plot on next slide shows the total number of
  active events in EVM without any involvement of
  filter nodes. We increment this total in RM on
  each arriving trigger. These events are assigned
  to BUs which make data requests to RUs. As soon
  as a particular BU builds a complete event, it
  immediately sends a clear request to BM to clear
  this event ID and clear its resource. The active
  number total is decremented each time when BM
  receives a clear event request from any BU

6
EVM with 0ms FPT
7
EVM with 40ms FPT

• The next plot shows the active events in the
  system with 40 ms farm processing time.

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