[tor-commits] [torflow/master] Allow us to cap feedback via consensus param.

[mikeperry at torproject.org]

commit 0300422f1f9a1c9ab6df2344a343898ee545082f
Author: Mike Perry <mikeperry-git at fscked.org>
Date:   Sat Dec 3 16:53:44 2011 -0800

    Allow us to cap feedback via consensus param.
    
    Also demote a couple logs, and add a couple more.
---
 NetworkScanners/BwAuthority/README.spec.txt |    7 +++++++
 NetworkScanners/BwAuthority/aggregate.py    |   22 ++++++++++++++++++++--
 2 files changed, 27 insertions(+), 2 deletions(-)

diff --git a/NetworkScanners/BwAuthority/README.spec.txt b/NetworkScanners/BwAuthority/README.spec.txt
index e46994c..5eb0661 100644
--- a/NetworkScanners/BwAuthority/README.spec.txt
+++ b/NetworkScanners/BwAuthority/README.spec.txt
@@ -577,3 +577,10 @@
        for the values of T_i that are relevant to us.
 
        If T_i is 0 or absent, K_i_decay is set to 0.
+
+    "bwauthpidmax=N"
+       Caps pid_error_sum feedback to N/10000.0. Can be used to prevent
+       runaway feedback loops for fast nodes.
+
+       If absent, the default is 500.0, which translates to a 501X
+       multiplier of descriptor bandwidth.
diff --git a/NetworkScanners/BwAuthority/aggregate.py b/NetworkScanners/BwAuthority/aggregate.py
index ca26b2d..7af68aa 100755
--- a/NetworkScanners/BwAuthority/aggregate.py
+++ b/NetworkScanners/BwAuthority/aggregate.py
@@ -242,6 +242,7 @@ class ConsensusJunk:
     self.use_desc_bw = True
     self.use_mercy = False
 
+    self.pid_max = 500.0
     self.K_p = K_p
     self.T_i = T_i
     self.T_d = T_d
@@ -283,6 +284,9 @@ class ConsensusJunk:
         elif p.startswith("bwauthtidecay="):
           self.T_i_decay = (int(p.split("=")[1])/10000.0)
           plog("INFO", "Got T_i_decay=%f from consensus." % self.T_i_decay)
+        elif p.startswith("bwauthpidmax="):
+          self.pid_max = (int(p.split("=")[1])/10000.0)
+          plog("INFO", "Got pid_max=%f from consensus." % self.pid_max)
     except:
       plog("NOTICE", "Bw auth PID control disabled due to parse error.")
       traceback.print_exc()
@@ -596,8 +600,22 @@ def main(argv):
           # If node was demoted in the past and we plan to demote it again,
           # let's just not and say we did.
           if n.desc_bw > n.ns_bw and n.pid_error < 0:
+            plog("INFO", "Showing mercy for node "+n.nick+"="+n.idhex)
             n.use_bw = n.desc_bw
         if n.pid_error_sum < 0 and n.pid_error < 0:
+          plog("INFO", "Showing mercy for node "+n.nick+"="+n.idhex+", pid_error_sum="+str(n.pid_error_sum))
+          n.pid_error_sum = 0
+
+      # Similarly, don't accumulate too much amplification for
+      # fast nodes
+      if cs_junk.use_desc_bw:
+        if n.pid_error_sum > cs_junk.pid_max and n.pid_error > 0:
+          plog("INFO", "Capping feedback for node "+n.nick+"="+n.idhex+", pid_error_sum="+str(n.pid_error_sum))
+          n.pid_error_sum = cs_junk.pid_max
+      else:
+        if float(n.ns_bw)/n.desc_bw > cs_junk.pid_max and n.pid_error > 0:
+          plog("INFO", "Capping feedback for node "+n.nick+"="+n.idhex)
+          n.pid_error = 0
           n.pid_error_sum = 0
 
       if n.idhex in prev_votes.vote_map:
@@ -669,7 +687,7 @@ def main(argv):
         n.new_bw = n.use_bw + cs_junk.K_p*n.use_bw*n.pid_error
         n.pid_error_sum = n.pid_error
         n.pid_bw = n.new_bw
-        plog("INFO", "No prev vote for node "+n.nick+": Consensus feedback")
+        plog("DEBUG", "No prev vote for node "+n.nick+": Consensus feedback")
     else: # No PID feedback
       # Choose the larger between sbw and fbw
       if n.sbw_ratio > n.fbw_ratio:
@@ -694,7 +712,7 @@ def main(argv):
         plog("INFO", "Skipping voting for guard "+n.nick)
         n.ignore = True
       elif "Authority" in prev_consensus[n.idhex].flags:
-        plog("INFO", "Skipping voting for authority "+n.nick)
+        plog("DEBUG", "Skipping voting for authority "+n.nick)
         n.ignore = True
 
   # Go through the list and cap them to NODE_CAP