shill: update the bgscan parameters
We identified that shill is very aggressive with the
background scan parameters.
The threshold between short and long interval is very low,
meaning that even when the signal is very strong, we'll fire
a scan very often. Fix this by doing two things:
1) Raise the threshold for short scan internal to -72db
2) Lower the scan frequency when we have a low RSSI to a
minute (64 seconds to take the approximate scan duration
into account).
On the way, increase the frequency of the scan when we have
a good RSSI to 6 minutes. Waiting for an hour to issue a
scan is really long.
BUG=b:111071506
TEST=Build and deploy on Eve in Google desk area. Note number of roams
before and after the bgscan parameter change.
Change-Id: If7c57e0375af4a38d3ad5627b10497d243be0068
diff --git a/wifi/wifi.cc b/wifi/wifi.cc
index 285ff84..e416a39 100644
--- a/wifi/wifi.cc
+++ b/wifi/wifi.cc
@@ -83,13 +83,13 @@
// statics
const char* const WiFi::kDefaultBgscanMethod =
WPASupplicant::kNetworkBgscanMethodSimple;
-const uint16_t WiFi::kDefaultBgscanShortIntervalSeconds = 30;
-const int32_t WiFi::kDefaultBgscanSignalThresholdDbm = -62;
+const uint16_t WiFi::kDefaultBgscanShortIntervalSeconds = 64;
+const int32_t WiFi::kDefaultBgscanSignalThresholdDbm = -72;
const uint16_t WiFi::kDefaultScanIntervalSeconds = 60;
const uint16_t WiFi::kDefaultRoamThresholdDb = 18; // Supplicant's default.
// Scan interval while connected.
-const uint16_t WiFi::kBackgroundScanIntervalSeconds = 3601;
+const uint16_t WiFi::kBackgroundScanIntervalSeconds = 360;
// Age (in seconds) beyond which a BSS cache entry will not be preserved,
// across a suspend/resume.
const time_t WiFi::kMaxBSSResumeAgeSeconds = 10;
