commit 24bf42c5938bf996c878ddd1ad25c442e6128e69 Author: Mike Perry <mikeperry-git@fscked.org> Date: Mon Oct 31 23:48:02 2011 -0700 Update spec with circ failure info. --- NetworkScanners/BwAuthority/README.spec.txt | 12 +++++++++--- 1 files changed, 9 insertions(+), 3 deletions(-) diff --git a/NetworkScanners/BwAuthority/README.spec.txt b/NetworkScanners/BwAuthority/README.spec.txt index a4e793e..377841c 100644 --- a/NetworkScanners/BwAuthority/README.spec.txt +++ b/NetworkScanners/BwAuthority/README.spec.txt @@ -369,10 +369,16 @@ 3.1. Modeling Measurement as PID Control The bandwidth authorities measure F_node: the filtered stream - capacity through a given node (filtering is described in Section 1.6). + capacity through a given node (filtering is described in Section 1.6) + times the circuit success rate of circuit EXTENDs to the node + (1.0 - circ_fail_rate). - The PID Setpoint, or target for each node is F_avg: the average filtered - stream capacity observed in the network + In PID control, we add in this extra failure rate as a damper, to prevent + the PID control system from driving nodes to CPU overload. Once nodes + begin failing circuits, we want to stop devoting more capacity. + + The PID Setpoint, or target for each node is F_avg: the average F_node + value observed across the entire network. The normalized PID error e(t) for each node is then: