Fix oinkmaster patch.

[ipfire-2.x.git] / src / patches / suse-2.6.27.39 / patches.drivers / fcoe-improved-load-balancing-i.diff

From: Vasu Dev <vasu.dev@intel.com>
Subject: [FcOE] improved load balancing in rx path
References: bnc #459142

Currently incoming frame exchange id ANDing with total number of bits
in online CPU bits mask, resulted only at most two CPUs selection in
rx path, so instead used online CPU bits mask to direct incoming frame
to a all cpus for better load balancing.

Added code to default to first CPU in case selected CPU is offline or
its rx thread not present.

Signed-off-by: Vasu Dev <vasu.dev@intel.com>
Acked-by: Bernhard Walle <bwalle@suse.de>
---

 drivers/scsi/fcoe/libfcoe.c |   13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)


--- a/drivers/scsi/fcoe/libfcoe.c
+++ b/drivers/scsi/fcoe/libfcoe.c
@@ -230,13 +230,14 @@ int fcoe_rcv(struct sk_buff *skb, struct
 	cpu_idx = 0;
 #ifdef CONFIG_SMP
 	/*
-	 * The exchange ID are ANDed with num of online CPUs,
-	 * so that will have the least lock contention in
-	 * handling the exchange. if there is no thread
-	 * for a given idx then use first online cpu.
+	 * The incoming frame exchange id(oxid) is ANDed with num of online
+	 * cpu bits to get cpu_idx and then this cpu_idx is used for selecting
+	 * a per cpu kernel thread from fcoe_percpu. In case the cpu is
+	 * offline or no kernel thread for derived cpu_idx then cpu_idx is
+	 * initialize to first online cpu index.
 	 */
-	cpu_idx = oxid & (num_online_cpus() >> 1);
-	if (fcoe_percpu[cpu_idx] == NULL)
+	cpu_idx = oxid & (num_online_cpus() - 1);
+	if (!fcoe_percpu[cpu_idx] || !cpu_online(cpu_idx))
 		cpu_idx = first_cpu(cpu_online_map);
 #endif
 	fps = fcoe_percpu[cpu_idx];