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Commit e6ded99c authored by Roland Dreier's avatar Roland Dreier Committed by Linus Torvalds
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[PATCH] IPoIB: fix static rate calculation 



Correct and simplify calculation of static rate.  We need to round up the
quotient of (local_rate - path_rate) / path_rate.  To round up we add
(path_rate - 1) to the numerator, so the quotient simplifies to (local_rate -
1) / path_rate.

No idea how I came up with the old formula.

Signed-off-by: default avatarRoland Dreier <roland@topspin.com>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 62241eb4

drivers/infiniband/ulp/ipoib/ipoib_main.c

+3 −4
Original line number Diff line number Diff line
@@ -302,11 +302,10 @@ static void path_rec_completion(int status, 
			.sl 	       = pathrec->sl,

			.port_num      = priv->port

		};

		int path_rate = ib_sa_rate_enum_to_int(pathrec->rate);



		if (ib_sa_rate_enum_to_int(pathrec->rate) > 0)

			av.static_rate = (2 * priv->local_rate -

					  ib_sa_rate_enum_to_int(pathrec->rate) - 1) /

				(priv->local_rate ? priv->local_rate : 1);

		if (path_rate > 0 && priv->local_rate > path_rate)

			av.static_rate = (priv->local_rate - 1) / path_rate;



		ipoib_dbg(priv, "static_rate %d for local port %dX, path %dX\n",

			  av.static_rate, priv->local_rate,

drivers/infiniband/ulp/ipoib/ipoib_multicast.c

+3 −4
Original line number Diff line number Diff line
@@ -258,13 +258,12 @@ static int ipoib_mcast_join_finish(struct ipoib_mcast *mcast, 
				.traffic_class = mcast->mcmember.traffic_class

			}

		};

		int path_rate = ib_sa_rate_enum_to_int(mcast->mcmember.rate);



		av.grh.dgid = mcast->mcmember.mgid;



		if (ib_sa_rate_enum_to_int(mcast->mcmember.rate) > 0)

			av.static_rate = (2 * priv->local_rate -

					  ib_sa_rate_enum_to_int(mcast->mcmember.rate) - 1) /

				(priv->local_rate ? priv->local_rate : 1);

		if (path_rate > 0 && priv->local_rate > path_rate)

			av.static_rate = (priv->local_rate - 1) / path_rate;



		ipoib_dbg_mcast(priv, "static_rate %d for local port %dX, mcmember %dX\n",

				av.static_rate, priv->local_rate,