[CELL] cell: add placement computation for scheduling of affinity contexts
This patch provides the spu affinity placement logic for the spufs scheduler.
Each time a gang is going to be scheduled, the placement of a reference
context is defined. The placement of all other contexts with affinity from
the gang is defined based on this reference context location and on a
precomputed displacement offset.
Signed-off-by: Andre Detsch <adetsch@br.ibm.com>
Signed-off-by: Arnd Bergmann <arnd.bergmann@de.ibm.com>
diff --git a/arch/powerpc/platforms/cell/spufs/gang.c b/arch/powerpc/platforms/cell/spufs/gang.c
index 0a752ce..71a4432 100644
--- a/arch/powerpc/platforms/cell/spufs/gang.c
+++ b/arch/powerpc/platforms/cell/spufs/gang.c
@@ -75,8 +75,10 @@
{
mutex_lock(&gang->mutex);
WARN_ON(ctx->gang != gang);
- if (!list_empty(&ctx->aff_list))
+ if (!list_empty(&ctx->aff_list)) {
list_del_init(&ctx->aff_list);
+ gang->aff_flags &= ~AFF_OFFSETS_SET;
+ }
list_del_init(&ctx->gang_list);
gang->contexts--;
mutex_unlock(&gang->mutex);
diff --git a/arch/powerpc/platforms/cell/spufs/sched.c b/arch/powerpc/platforms/cell/spufs/sched.c
index 6d0ab72..a9569de 100644
--- a/arch/powerpc/platforms/cell/spufs/sched.c
+++ b/arch/powerpc/platforms/cell/spufs/sched.c
@@ -233,6 +233,8 @@
if (ctx->flags & SPU_CREATE_NOSCHED)
atomic_inc(&cbe_spu_info[spu->node].reserved_spus);
+ if (!list_empty(&ctx->aff_list))
+ atomic_inc(&ctx->gang->aff_sched_count);
ctx->stats.slb_flt_base = spu->stats.slb_flt;
ctx->stats.class2_intr_base = spu->stats.class2_intr;
@@ -259,6 +261,143 @@
spuctx_switch_state(ctx, SPU_UTIL_IDLE_LOADED);
}
+/*
+ * XXX(hch): needs locking.
+ */
+static inline int sched_spu(struct spu *spu)
+{
+ return (!spu->ctx || !(spu->ctx->flags & SPU_CREATE_NOSCHED));
+}
+
+static void aff_merge_remaining_ctxs(struct spu_gang *gang)
+{
+ struct spu_context *ctx;
+
+ list_for_each_entry(ctx, &gang->aff_list_head, aff_list) {
+ if (list_empty(&ctx->aff_list))
+ list_add(&ctx->aff_list, &gang->aff_list_head);
+ }
+ gang->aff_flags |= AFF_MERGED;
+}
+
+static void aff_set_offsets(struct spu_gang *gang)
+{
+ struct spu_context *ctx;
+ int offset;
+
+ offset = -1;
+ list_for_each_entry_reverse(ctx, &gang->aff_ref_ctx->aff_list,
+ aff_list) {
+ if (&ctx->aff_list == &gang->aff_list_head)
+ break;
+ ctx->aff_offset = offset--;
+ }
+
+ offset = 0;
+ list_for_each_entry(ctx, gang->aff_ref_ctx->aff_list.prev, aff_list) {
+ if (&ctx->aff_list == &gang->aff_list_head)
+ break;
+ ctx->aff_offset = offset++;
+ }
+
+ gang->aff_flags |= AFF_OFFSETS_SET;
+}
+
+static struct spu *aff_ref_location(struct spu_context *ctx, int mem_aff,
+ int group_size, int lowest_offset)
+{
+ struct spu *spu;
+ int node, n;
+
+ /*
+ * TODO: A better algorithm could be used to find a good spu to be
+ * used as reference location for the ctxs chain.
+ */
+ node = cpu_to_node(raw_smp_processor_id());
+ for (n = 0; n < MAX_NUMNODES; n++, node++) {
+ node = (node < MAX_NUMNODES) ? node : 0;
+ if (!node_allowed(ctx, node))
+ continue;
+ list_for_each_entry(spu, &cbe_spu_info[node].spus, cbe_list) {
+ if ((!mem_aff || spu->has_mem_affinity) &&
+ sched_spu(spu))
+ return spu;
+ }
+ }
+ return NULL;
+}
+
+static void aff_set_ref_point_location(struct spu_gang *gang)
+{
+ int mem_aff, gs, lowest_offset;
+ struct spu_context *ctx;
+ struct spu *tmp;
+
+ mem_aff = gang->aff_ref_ctx->flags & SPU_CREATE_AFFINITY_MEM;
+ lowest_offset = 0;
+ gs = 0;
+
+ list_for_each_entry(tmp, &gang->aff_list_head, aff_list)
+ gs++;
+
+ list_for_each_entry_reverse(ctx, &gang->aff_ref_ctx->aff_list,
+ aff_list) {
+ if (&ctx->aff_list == &gang->aff_list_head)
+ break;
+ lowest_offset = ctx->aff_offset;
+ }
+
+ gang->aff_ref_spu = aff_ref_location(ctx, mem_aff, gs, lowest_offset);
+}
+
+static struct spu *ctx_location(struct spu *ref, int offset)
+{
+ struct spu *spu;
+
+ spu = NULL;
+ if (offset >= 0) {
+ list_for_each_entry(spu, ref->aff_list.prev, aff_list) {
+ if (offset == 0)
+ break;
+ if (sched_spu(spu))
+ offset--;
+ }
+ } else {
+ list_for_each_entry_reverse(spu, ref->aff_list.next, aff_list) {
+ if (offset == 0)
+ break;
+ if (sched_spu(spu))
+ offset++;
+ }
+ }
+ return spu;
+}
+
+/*
+ * affinity_check is called each time a context is going to be scheduled.
+ * It returns the spu ptr on which the context must run.
+ */
+struct spu *affinity_check(struct spu_context *ctx)
+{
+ struct spu_gang *gang;
+
+ if (list_empty(&ctx->aff_list))
+ return NULL;
+ gang = ctx->gang;
+ mutex_lock(&gang->aff_mutex);
+ if (!gang->aff_ref_spu) {
+ if (!(gang->aff_flags & AFF_MERGED))
+ aff_merge_remaining_ctxs(gang);
+ if (!(gang->aff_flags & AFF_OFFSETS_SET))
+ aff_set_offsets(gang);
+ aff_set_ref_point_location(gang);
+ }
+ mutex_unlock(&gang->aff_mutex);
+ if (!gang->aff_ref_spu)
+ return NULL;
+ return ctx_location(gang->aff_ref_spu, ctx->aff_offset);
+}
+
/**
* spu_unbind_context - unbind spu context from physical spu
* @spu: physical spu to unbind from
@@ -272,6 +411,9 @@
if (spu->ctx->flags & SPU_CREATE_NOSCHED)
atomic_dec(&cbe_spu_info[spu->node].reserved_spus);
+ if (!list_empty(&ctx->aff_list))
+ if (atomic_dec_and_test(&ctx->gang->aff_sched_count))
+ ctx->gang->aff_ref_spu = NULL;
spu_switch_notify(spu, NULL);
spu_unmap_mappings(ctx);
spu_save(&ctx->csa, spu);
diff --git a/arch/powerpc/platforms/cell/spufs/spufs.h b/arch/powerpc/platforms/cell/spufs/spufs.h
index 36da179..42d8da8 100644
--- a/arch/powerpc/platforms/cell/spufs/spufs.h
+++ b/arch/powerpc/platforms/cell/spufs/spufs.h
@@ -112,6 +112,7 @@
struct list_head aff_list;
int aff_head;
+ int aff_offset;
};
struct spu_gang {
@@ -124,6 +125,8 @@
struct list_head aff_list_head;
struct mutex aff_mutex;
int aff_flags;
+ struct spu *aff_ref_spu;
+ atomic_t aff_sched_count;
};
/* Flag bits for spu_gang aff_flags */
@@ -208,6 +211,9 @@
/* fault handling */
int spufs_handle_class1(struct spu_context *ctx);
+/* affinity */
+struct spu *affinity_check(struct spu_context *ctx);
+
/* context management */
extern atomic_t nr_spu_contexts;
static inline void spu_acquire(struct spu_context *ctx)