[Cbe-oss-dev] [PATCH 5/6] spufs: add placement computation for scheduling of affinity contexts
Andre Detsch
adetsch at br.ibm.com
Mon Feb 12 12:16:45 EST 2007
Subject: spufs: add placement computation for scheduling of affinity contexts
From: Andre Detsch <adetsch at br.ibm.com>
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 at br.ibm.com>
Index: linux-2.6.20/arch/powerpc/platforms/cell/spufs/sched.c
===================================================================
--- linux-2.6.20.orig/arch/powerpc/platforms/cell/spufs/sched.c
+++ linux-2.6.20/arch/powerpc/platforms/cell/spufs/sched.c
@@ -141,6 +141,8 @@ static void spu_bind_context(struct spu
{
pr_debug("%s: pid=%d SPU=%d NODE=%d\n", __FUNCTION__, current->pid,
spu->number, spu->node);
+ if (ctx->aff_flags & (AFF_HAS_SPU_AFFINITY | AFF_HAS_MEM_AFFINITY))
+ atomic_inc(&ctx->gang->aff_sched_count);
spu->ctx = ctx;
spu->flags = 0;
ctx->spu = spu;
@@ -177,6 +179,11 @@ static int spu_unbind_context(struct spu
pr_debug("%s: unbind pid=%d SPU=%d NODE=%d\n", __FUNCTION__,
spu->pid, spu->number, spu->node);
+ if (ctx->aff_flags & (AFF_HAS_SPU_AFFINITY | AFF_HAS_MEM_AFFINITY)) {
+ if (atomic_dec_and_test(&ctx->gang->aff_sched_count))
+ ctx->gang->aff_ref_point_location = NULL;
+ }
+
spu_switch_notify(spu, NULL);
spu_unmap_mappings(ctx);
spu_save(&ctx->csa, spu);
@@ -413,3 +420,126 @@ void __exit spu_sched_exit(void)
}
kfree(spu_prio);
}
+
+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);
+ ctx->aff_flags |= AFF_HAS_SPU_AFFINITY;
+ }
+ }
+ gang->aff_flags |= AFF_MERGED;
+}
+
+static void aff_set_rel_displ(struct spu_gang *gang)
+{
+ struct spu_context *ctx;
+ int displacement;
+
+ displacement = -1;
+ list_for_each_entry_reverse(ctx, &gang->aff_ref_point->aff_list,
+ aff_list) {
+ if (&ctx->aff_list == &gang->aff_list_head)
+ break;
+ ctx->aff_rel_displ = displacement--;
+ }
+
+ displacement = 0;
+ list_for_each_entry(ctx, gang->aff_ref_point->aff_list.prev, aff_list) {
+ if (&ctx->aff_list == &gang->aff_list_head)
+ break;
+ ctx->aff_rel_displ = displacement++;
+ }
+
+ gang->aff_flags |= AFF_REL_DISPL_SET;
+}
+
+static struct spu *
+aff_ref_location(int mem_aff, int group_size, int prio, int lowest_rel_displ)
+{
+ struct spu *spu;
+ int node;
+
+ /* TODO: A better algorithm could be used to find a good spu to be
+ * used as reference location for the ctxs chain.
+ * Also, a isolated SPU should never be chosen here.
+ */
+ for (node = 0; node < MAX_NUMNODES; node++) {
+ list_for_each_entry(spu, &be_spu_info[node].available_spus,
+ available_list) {
+ if (!mem_aff || spu->has_mem_affinity)
+ return spu;
+ }
+ }
+ BUG_ON(1);
+ return NULL;
+}
+
+static void aff_set_ref_point_location(struct spu_gang *gang)
+{
+ int mem_aff, gs, lowest_rel_displ;
+ struct spu_context *ctx;
+ struct spu *tmp;
+
+ mem_aff = gang->aff_ref_point->aff_flags & AFF_HAS_MEM_AFFINITY;
+ lowest_rel_displ = 0;
+ gs = 0;
+ list_for_each_entry(tmp, &gang->aff_list_head, aff_list)
+ gs++;
+
+ list_for_each_entry_reverse(ctx, &gang->aff_ref_point->aff_list,
+ aff_list) {
+ if (&ctx->aff_list == &gang->aff_list_head)
+ break;
+ lowest_rel_displ = ctx->aff_rel_displ;
+ }
+
+ gang->aff_ref_point_location = aff_ref_location(mem_aff, gs, ctx->prio,
+ lowest_rel_displ);
+}
+
+static struct spu* ctx_location(struct spu *ref, int rel_displ)
+{
+ struct spu *spu;
+
+ /* TODO: skip isolated SPUs */
+ if (rel_displ >= 0) {
+ list_for_each_entry(spu, ref->aff_list.prev, aff_list) {
+ if (rel_displ == 0)
+ return spu;
+ rel_displ--;
+ }
+ } else {
+ list_for_each_entry_reverse(spu, ref->aff_list.next, aff_list) {
+ if (rel_displ == 0)
+ return spu;
+ rel_displ++;
+ }
+ }
+ return NULL;
+}
+
+/**
+ * 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;
+ if (!gang->aff_ref_point_location) {
+ if (!gang->aff_flags & AFF_MERGED)
+ aff_merge_remaining_ctxs(gang);
+ if (!gang->aff_flags & AFF_REL_DISPL_SET)
+ aff_set_rel_displ(gang);
+ aff_set_ref_point_location(gang);
+ }
+ BUG_ON(!gang->aff_ref_point_location);
+ return ctx_location(gang->aff_ref_point_location, ctx->aff_rel_displ);
+}
Index: linux-2.6.20/arch/powerpc/platforms/cell/spufs/spufs.h
===================================================================
--- linux-2.6.20.orig/arch/powerpc/platforms/cell/spufs/spufs.h
+++ linux-2.6.20/arch/powerpc/platforms/cell/spufs/spufs.h
@@ -85,6 +85,7 @@ struct spu_context {
struct list_head aff_list;
int aff_flags;
+ int aff_rel_displ;
};
/* Flag bits for spu_context aff_flags */
@@ -102,6 +103,8 @@ struct spu_gang {
struct list_head aff_list_head;
struct mutex aff_mutex;
int aff_flags;
+ struct spu *aff_ref_point_location;
+ atomic_t aff_sched_count;
};
/* Flag bits for spu_gang aff_flags */
@@ -182,6 +185,9 @@ int put_spu_gang(struct spu_gang *gang);
void spu_gang_remove_ctx(struct spu_gang *gang, struct spu_context *ctx);
void spu_gang_add_ctx(struct spu_gang *gang, struct spu_context *ctx);
+/* affinity */
+struct spu *affinity_check(struct spu_context *ctx);
+
/* context management */
static inline void spu_acquire(struct spu_context *ctx)
{
Index: linux-2.6.20/arch/powerpc/platforms/cell/spufs/gang.c
===================================================================
--- linux-2.6.20.orig/arch/powerpc/platforms/cell/spufs/gang.c
+++ linux-2.6.20/arch/powerpc/platforms/cell/spufs/gang.c
@@ -39,6 +39,7 @@ struct spu_gang *alloc_spu_gang(void)
INIT_LIST_HEAD(&gang->list);
INIT_LIST_HEAD(&gang->aff_list_head);
+ gang->aff_ref_point_location = NULL;
out:
return gang;
}
@@ -77,8 +78,10 @@ void spu_gang_remove_ctx(struct spu_gang
WARN_ON(ctx->gang != gang);
list_del_init(&ctx->gang_list);
gang->contexts--;
- if (ctx->aff_flags & (AFF_HAS_SPU_AFFINITY | AFF_HAS_MEM_AFFINITY))
+ if (ctx->aff_flags & (AFF_HAS_SPU_AFFINITY | AFF_HAS_MEM_AFFINITY)) {
list_del(&ctx->aff_list);
+ gang->aff_flags &= ~AFF_REL_DISPL_SET;
+ }
mutex_unlock(&gang->mutex);
put_spu_gang(gang);
--
Andre Detsch
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