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Commit c5fc8d2a authored by Arnd Bergmann's avatar Arnd Bergmann Committed by Arnd Bergmann
Browse files

[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: default avatarAndre Detsch <adetsch@br.ibm.com>
Signed-off-by: default avatarArnd Bergmann <arnd.bergmann@de.ibm.com>
parent 8e68e2f2

arch/powerpc/platforms/cell/spufs/gang.c

+3 −1
Original line number Diff line number Diff line
@@ -75,8 +75,10 @@ void spu_gang_remove_ctx(struct spu_gang *gang, struct spu_context *ctx) 
{

	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);

arch/powerpc/platforms/cell/spufs/sched.c

+142 −0
Original line number Diff line number Diff line
@@ -233,6 +233,8 @@ static void spu_bind_context(struct spu *spu, struct spu_context *ctx) 


	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 @@ static void spu_bind_context(struct spu *spu, struct spu_context *ctx) 
	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 @@ static void spu_unbind_context(struct spu *spu, struct spu_context *ctx) 


 	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);

arch/powerpc/platforms/cell/spufs/spufs.h

+6 −0
Original line number Diff line number Diff line
@@ -112,6 +112,7 @@ struct spu_context { 


	struct list_head aff_list;

	int aff_head;

	int aff_offset;

};



struct spu_gang {
@@ -124,6 +125,8 @@ struct spu_gang { 
	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 @@ void spu_gang_add_ctx(struct spu_gang *gang, struct spu_context *ctx); 
/* 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)