commit 9121061d61d6fb8fd941c8f12c450d988f82ceae Author: Mike Perry mikeperry-git@fscked.org Date: Mon Oct 31 15:03:14 2011 -0700

Comments from arma. --- NetworkScanners/BwAuthority/README.spec.txt | 27 ++++++++++++++++++++++----- 1 files changed, 22 insertions(+), 5 deletions(-)

diff --git a/NetworkScanners/BwAuthority/README.spec.txt b/NetworkScanners/BwAuthority/README.spec.txt index ab67fd8..8aebaad 100644 --- a/NetworkScanners/BwAuthority/README.spec.txt +++ b/NetworkScanners/BwAuthority/README.spec.txt @@ -427,10 +427,17 @@ 3.3. Flag weighting

Guard+Exit nodes are treated as normal nodes in terms of measurement - frequency (measurements are reported as soon as they are ready), except - they are given a K_p of 1.0-Wgd (Wgd is the consensus bandwidth-weight for - selecting Guard+Exits for the Guard position: See dir-spec.txt Section - 3.4.3). + frequency (measurements are reported as soon as their slice results + are ready), except they are given a K_p of 1.0-Wgd (Wgd is the consensus + bandwidth-weight for selecting Guard+Exits for the Guard position: See + dir-spec.txt Section 3.4.3). + + K_p=1.0-Wgd isn't expected to be the optimal value, but we needed a + dampening factor to slow the feedback loop, and it seems as good of an + initial guess as any. Note that convergence towards zero error should + still happen eventually with this value, just at a slower rate. + + All other nodes are given K_p of 1.0.

3.4. Value storage

@@ -448,6 +455,16 @@ Internally, the source uses the Standard PID Form: https://en.wikipedia.org/wiki/PID_controller#Ideal_versus_standard_PID_form

+ The Standard PID Form sets K_i and K_d to be proportional to K_p and two + other constants that have more relation to convergence behaviors: + + K_i = K_p/T_i + K_d = K_d*T_d + We have selected T_i to be 5.0 (5 measurement intervals) and T_d to be 0.5 - (one half interval). + (one half interval). The belief is that any steady state error should be + correctable in 5 intervals, and the current rate of change of error + only gives us useful information for a fraction of a measurement + interval, until clients begin to migrate to the new measurements. +