powerpc/spufs: Improve search of node for contexts with SPU affinity

This patch improves redability of the code responsible for trying to find
a node with enough SPUs not committed to other affinity gangs.

An additional check is also added, to avoid taking into account gangs that
have no SPU affinity.

Signed-off-by: Andre Detsch <adetsch@br.ibm.com>
Signed-off-by: Jeremy Kerr <jk@ozlabs.org>

diff --git a/arch/powerpc/platforms/cell/spufs/sched.c b/arch/powerpc/platforms/cell/spufs/sched.c
index 67595bc380dc154465682f9be7f9c203d283bfe5..6253df5a436e6edcc144064a362cd80a65f59cf0 100644 (file)
--- a/arch/powerpc/platforms/cell/spufs/sched.c
+++ b/arch/powerpc/platforms/cell/spufs/sched.c
@@ -312,6 +312,15 @@ static struct spu *aff_ref_location(struct spu_context *ctx, int mem_aff,
         */
        node = cpu_to_node(raw_smp_processor_id());
        for (n = 0; n < MAX_NUMNODES; n++, node++) {
+               /*
+                * "available_spus" counts how many spus are not potentially
+                * going to be used by other affinity gangs whose reference
+                * context is already in place. Although this code seeks to
+                * avoid having affinity gangs with a summed amount of
+                * contexts bigger than the amount of spus in the node,
+                * this may happen sporadically. In this case, available_spus
+                * becomes negative, which is harmless.
+                */
                int available_spus;
 
                node = (node < MAX_NUMNODES) ? node : 0;
@@ -321,12 +330,10 @@ static struct spu *aff_ref_location(struct spu_context *ctx, int mem_aff,
                available_spus = 0;
                mutex_lock(&cbe_spu_info[node].list_mutex);
                list_for_each_entry(spu, &cbe_spu_info[node].spus, cbe_list) {
-                       if (spu->ctx && spu->ctx->gang
-                                       && spu->ctx->aff_offset == 0)
-                               available_spus -=
-                                       (spu->ctx->gang->contexts - 1);
-                       else
-                               available_spus++;
+                       if (spu->ctx && spu->ctx->gang && !spu->ctx->aff_offset
+                                       && spu->ctx->gang->aff_ref_spu)
+                               available_spus -= spu->ctx->gang->contexts;
+                       available_spus++;
                }
                if (available_spus < ctx->gang->contexts) {
                        mutex_unlock(&cbe_spu_info[node].list_mutex);