Changes between Version 15 and Version 16 of CreditNew

Timestamp:

Nov 16, 2009, 12:06:40 PM (15 years ago)

Author:

davea

Comment:

--

CreditNew

@@ -688 +688 @@
 This is called "cherry picking".
 
-Note: the host punishment mechanism
+The host punishment mechanism
 doesn't deal effectively with cherry picking,
 
 We propose the following mechanism to deal with cherry picking:
 
- * For each (host, app version), maintain "host_scale_time".
+ * For each (host, app version) maintain "host_scale_time".
    This is the earliest time at which host scaling will be applied.
-   This is set initially, and each time a job times out
-   or errors out, to now+X, where X is the app's delay bound.
+ * for each (host, app version) maintain "scale_probation"
+   (initially true).
+ * When send a job to a host,
+   if scale_probation is true,
+   set host_scale_time to now+X, where X is the app's delay bound.
+ * When a job is successfully validated,
+   and now > host_scale_time,
+   set scale_probation to false.
+ * If a job times out or errors out,
+   set scale_probation to true,
+   max the scale factor with 1,
+   and set host_scale_time to now+X.
+ * when computing claimed credit for a job,
+   and now < host_scale_time, don't use the host scale factor
 
 The idea is to apply the host scaling factor
 only if there's solid evidence that the host is NOT cherry picking.
+
+In addition, to limit the extent of cheating
+(in case the above mechanism is defeated somehow)
+the host scaling factor will be min'd with a configurable parameters (say, 3).
 
 == Implementation ==