commit 67e275b473289f9f511af6a0a2181422e6004406 Author: Mike Perry mikeperry-git@fscked.org Date: Mon Oct 31 15:37:55 2011 -0700

Add Guard non-feedback info to spec.

Yeah, this is confusing.. But arma thinks it's a good idea. --- NetworkScanners/BwAuthority/README.spec.txt | 21 ++++++++++++++------- 1 files changed, 14 insertions(+), 7 deletions(-)

diff --git a/NetworkScanners/BwAuthority/README.spec.txt b/NetworkScanners/BwAuthority/README.spec.txt index 8aebaad..a4e793e 100644 --- a/NetworkScanners/BwAuthority/README.spec.txt +++ b/NetworkScanners/BwAuthority/README.spec.txt @@ -397,23 +397,29 @@ new_bw = old_bw*F_node/F_avg new_bw = old_bw*ratio

-3.2. Measurement intervals +3.2. Measurement intervals and Feedback intervals

In order to prevent the consensus bandwidth from functioning as an accumulator (thus amplifying the effects of integration), we must - carefully tune the measurement intervals to a rate that we can - expect clients to respond to. + tune the feedback intervals to a rate that we can expect clients + to respond to.

For non-Guard nodes, this is basically 4 consensus intervals, or 4 hours. Since the bandwidth authorities also take on the order of hours to measure a slice of nodes, we do nothing special here.

- For Guard nodes however, clients have an minimum rotation rate of 4-6 + For Guard nodes however, clients have minimum rotation rate of 4-6 weeks. However, on the assumption that they rotate more frequently - than this, we set our Guard measurement interval to 2 weeks. + than this, we set our Guard feedback interval to 2 weeks. + + Guard measurements are also used without feedback whenever new + measurements are available, to compensate for changes in Guard flag + status and associated load changes. These new measurements are + multiplied by our most recent bandwidth value that used feedback, + in a similar way to Section 2.2.

For purposes of calculating the integral and the derivative of the - error, we assume units of time that correspond to measurement intervals, + error, we assume units of time that correspond to feedback intervals, eliminating the need to track time for any other purpose other than determining when to report a measurement.

@@ -446,7 +452,8 @@

"pid_error=" (PID error term as defined in Section 3.1) SP "pid_error_sum=" (Weighted sum of PID error) SP - "pid_delta=" (Change in error) NL + "pid_delta=" (Change in error) SP + "pid_bw=" (Last bandwidth value used in feedback) NL

pid_delta is purely informational, and is not used in feedback.