From: Javier Cardona Date: Thu, 12 Apr 2012 21:32:23 +0000 (-0700) Subject: mac80211: Take into account TSF adjustment latency in Toffset setpoint X-Git-Tag: v3.5-rc1~109^2~410^2~46 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=ec14bcd20f5139a3dc42cfc34cdcebcbdc062c00;p=platform%2Fkernel%2Flinux-3.10.git mac80211: Take into account TSF adjustment latency in Toffset setpoint When testing mesh synchronization we observed a global TSF slowdown that was dependent on the number of synchronized mesh stations. This seems to be caused by the TSF adjustment (read/write) latency. Adding a small margin to the Toffset setpoint solved the problem. Signed-off-by: Shinichi Hotori Signed-off-by: Yu Niiro Signed-off-by: Javier Cardona Signed-off-by: John W. Linville --- diff --git a/net/mac80211/mesh_sync.c b/net/mac80211/mesh_sync.c index 22a5f1e..ff60d6b 100644 --- a/net/mac80211/mesh_sync.c +++ b/net/mac80211/mesh_sync.c @@ -24,11 +24,17 @@ */ #define TOFFSET_MINIMUM_ADJUSTMENT 10 +/* This is not in the standard. It is a margin added to the + * Toffset setpoint to mitigate TSF overcorrection + * introduced by TSF adjustment latency. + */ +#define TOFFSET_SET_MARGIN 20 + /* This is not in the standard. It represents the maximum Toffset jump above * which we'll invalidate the Toffset setpoint and choose a new setpoint. This * could be, for instance, in case a neighbor is restarted and its TSF counter * reset. - * */ + */ #define TOFFSET_MAXIMUM_ADJUSTMENT 30000 /* 30 ms */ struct sync_method {