coll/han: implement hierarchical scatterv

Add scatterv implementation to optimize large-scale communications on
multiple nodes and multiple processes per node, by avoiding high-incast
traffic on the root process.

Because *V collectives do not have equal datatype/count on every
process, it does not natively support message-size based tuning without
an additional global communication.

Similar to scatter, the hierarchical scatterv requires a
temporary buffer and memory copy to handle out-of-order data, or
non-contiguous placement on the send buffer, which results in worse
performance for large messages compared to the linear implementation.

Signed-off-by: Jessie Yang <[email protected]>

ompi/mca/coll/han/Makefile.am

@@ -21,6 +21,7 @@ coll_han_barrier.c \
 coll_han_bcast.c \
 coll_han_reduce.c \
 coll_han_scatter.c \
+coll_han_scatterv.c \
 coll_han_gather.c \
 coll_han_gatherv.c \
 coll_han_allreduce.c \

ompi/mca/coll/han/coll_han.h

@@ -193,6 +193,7 @@ typedef struct mca_coll_han_op_module_name_t {
     mca_coll_han_op_up_low_module_name_t gather;
     mca_coll_han_op_up_low_module_name_t gatherv;
     mca_coll_han_op_up_low_module_name_t scatter;
+    mca_coll_han_op_up_low_module_name_t scatterv;
 } mca_coll_han_op_module_name_t;
 
 /**
@@ -244,6 +245,10 @@ typedef struct mca_coll_han_component_t {
     uint32_t han_scatter_up_module;
     /* low level module for scatter */
     uint32_t han_scatter_low_module;
+    /* up level module for scatterv */
+    uint32_t han_scatterv_up_module;
+    /* low level module for scatterv */
+    uint32_t han_scatterv_low_module;
     /* name of the modules */
     mca_coll_han_op_module_name_t han_op_module_name;
     /* whether we need reproducible results
@@ -287,6 +292,7 @@ typedef struct mca_coll_han_single_collective_fallback_s {
         mca_coll_base_module_gatherv_fn_t gatherv;
         mca_coll_base_module_reduce_fn_t reduce;
         mca_coll_base_module_scatter_fn_t scatter;
+        mca_coll_base_module_scatterv_fn_t scatterv;
     } module_fn;
     mca_coll_base_module_t* module;
 } mca_coll_han_single_collective_fallback_t;
@@ -306,6 +312,7 @@ typedef struct mca_coll_han_collectives_fallback_s {
     mca_coll_han_single_collective_fallback_t gather;
     mca_coll_han_single_collective_fallback_t gatherv;
     mca_coll_han_single_collective_fallback_t scatter;
+    mca_coll_han_single_collective_fallback_t scatterv;
 } mca_coll_han_collectives_fallback_t;
 
 /** Coll han module */
@@ -384,6 +391,8 @@ OBJ_CLASS_DECLARATION(mca_coll_han_module_t);
 #define previous_scatter            fallback.scatter.module_fn.scatter
 #define previous_scatter_module     fallback.scatter.module
 
+#define previous_scatterv           fallback.scatterv.module_fn.scatterv
+#define previous_scatterv_module    fallback.scatterv.module
 
 /* macro to correctly load a fallback collective module */
 #define HAN_LOAD_FALLBACK_COLLECTIVE(HANM, COMM, COLL)                            \
@@ -403,6 +412,7 @@ OBJ_CLASS_DECLARATION(mca_coll_han_module_t);
         HAN_LOAD_FALLBACK_COLLECTIVE(HANM, COMM, barrier);                   \
         HAN_LOAD_FALLBACK_COLLECTIVE(HANM, COMM, bcast);                     \
         HAN_LOAD_FALLBACK_COLLECTIVE(HANM, COMM, scatter);                   \
+        HAN_LOAD_FALLBACK_COLLECTIVE(HANM, COMM, scatterv);                  \
         HAN_LOAD_FALLBACK_COLLECTIVE(HANM, COMM, gather);                    \
         HAN_LOAD_FALLBACK_COLLECTIVE(HANM, COMM, gatherv);                    \
         HAN_LOAD_FALLBACK_COLLECTIVE(HANM, COMM, reduce);                    \
@@ -495,6 +505,9 @@ mca_coll_han_reduce_intra_dynamic(REDUCE_BASE_ARGS,
 int
 mca_coll_han_scatter_intra_dynamic(SCATTER_BASE_ARGS,
                                    mca_coll_base_module_t *module);
+int
+mca_coll_han_scatterv_intra_dynamic(SCATTERV_BASE_ARGS,
+                                    mca_coll_base_module_t *module);
 
 int mca_coll_han_barrier_intra_simple(struct ompi_communicator_t *comm,
                                       mca_coll_base_module_t *module);

ompi/mca/coll/han/coll_han_algorithms.c

@@ -59,6 +59,10 @@ mca_coll_han_algorithm_value_t*  mca_coll_han_available_algorithms[COLLCOUNT] =
         {"simple", (fnptr_t) &mca_coll_han_scatter_intra_simple}, // 2-level
         { 0 }
     },
+    [SCATTERV] = (mca_coll_han_algorithm_value_t[]){
+        {"intra", (fnptr_t) &mca_coll_han_scatterv_intra}, // 2-level
+        { 0 }
+    },
     [GATHER] = (mca_coll_han_algorithm_value_t[]){
         {"intra", (fnptr_t) &mca_coll_han_gather_intra}, // 2-level
         {"simple", (fnptr_t) &mca_coll_han_gather_intra_simple}, // 2-level

ompi/mca/coll/han/coll_han_algorithms.h

@@ -159,6 +159,16 @@ mca_coll_han_scatter_intra_simple(const void *sbuf, int scount,
                                   struct ompi_communicator_t *comm,
                                   mca_coll_base_module_t * module);
 
+/* Scatterv */
+int
+mca_coll_han_scatterv_intra(const void *sbuf, const int *scounts,
+                            const int *displs, struct ompi_datatype_t *sdtype,
+                            void *rbuf, int rcount,
+                            struct ompi_datatype_t *rdtype, 
+                            int root,
+                            struct ompi_communicator_t *comm,
+                            mca_coll_base_module_t *module);
+
 /* Gather */
 int
 mca_coll_han_gather_intra(const void *sbuf, int scount,

ompi/mca/coll/han/coll_han_component.c

@@ -156,6 +156,11 @@ static int han_close(void)
     free(mca_coll_han_component.han_op_module_name.scatter.han_op_low_module_name);
     mca_coll_han_component.han_op_module_name.scatter.han_op_low_module_name = NULL;
 
+    free(mca_coll_han_component.han_op_module_name.scatterv.han_op_up_module_name);
+    mca_coll_han_component.han_op_module_name.scatterv.han_op_up_module_name = NULL;
+    free(mca_coll_han_component.han_op_module_name.scatterv.han_op_low_module_name);
+    mca_coll_han_component.han_op_module_name.scatterv.han_op_low_module_name = NULL;
+
     return OMPI_SUCCESS;
 }
 
@@ -373,6 +378,18 @@ static int han_register(void)
                                               OPAL_INFO_LVL_9, &cs->han_scatter_low_module,
                                               &cs->han_op_module_name.scatter.han_op_low_module_name);
 
+    cs->han_scatterv_up_module = 0;
+    (void) mca_coll_han_query_module_from_mca(c, "scatterv_up_module",
+                                              "up level module for scatterv, 0 basic",
+                                              OPAL_INFO_LVL_9, &cs->han_scatterv_up_module,
+                                              &cs->han_op_module_name.scatterv.han_op_up_module_name);
+
+    cs->han_scatterv_low_module = 0;
+    (void) mca_coll_han_query_module_from_mca(c, "scatterv_low_module",
+                                              "low level module for scatterv, 0 basic",
+                                              OPAL_INFO_LVL_9, &cs->han_scatterv_low_module,
+                                              &cs->han_op_module_name.scatterv.han_op_low_module_name);
+
     cs->han_reproducible = 0;
     (void) mca_base_component_var_register(c, "reproducible",
                                            "whether we need reproducible results "

ompi/mca/coll/han/coll_han_dynamic.c

@@ -46,6 +46,7 @@ bool mca_coll_han_is_coll_dynamic_implemented(COLLTYPE_T coll_id)
     case GATHERV:
     case REDUCE:
     case SCATTER:
+    case SCATTERV:
         return true;
     default:
         return false;
@@ -1397,3 +1398,113 @@ mca_coll_han_scatter_intra_dynamic(const void *sbuf, int scount,
                    root, comm,
                    sub_module);
 }
+
+
+/*
+ * Scatterv selector:
+ * On a sub-communicator, checks the stored rules to find the module to use
+ * On the global communicator, calls the han collective implementation, or
+ * calls the correct module if fallback mechanism is activated
+ */
+int
+mca_coll_han_scatterv_intra_dynamic(const void *sbuf, const int *scounts,
+                                    const int *displs, struct ompi_datatype_t *sdtype,
+                                    void *rbuf, int rcount,
+                                    struct ompi_datatype_t *rdtype, 
+                                    int root,
+                                    struct ompi_communicator_t *comm,
+                                    mca_coll_base_module_t *module)
+{
+    mca_coll_han_module_t *han_module = (mca_coll_han_module_t*) module;
+    TOPO_LVL_T topo_lvl = han_module->topologic_level;
+    mca_coll_base_module_scatterv_fn_t scatterv;
+    mca_coll_base_module_t *sub_module;
+    int rank, verbosity = 0;
+
+    if (!han_module->enabled) {
+        return han_module->previous_scatterv(sbuf, scounts, displs, sdtype, rbuf, rcount, rdtype, 
+                                             root, comm, han_module->previous_scatterv_module);
+    }
+
+    /* v collectives do not support message-size based dynamic rules */
+    sub_module = get_module(SCATTERV,
+                            MCA_COLL_HAN_ANY_MESSAGE_SIZE,
+                            comm,
+                            han_module);
+
+    /* First errors are always printed by rank 0 */
+    rank = ompi_comm_rank(comm);
+    if( (0 == rank) && (han_module->dynamic_errors < mca_coll_han_component.max_dynamic_errors) ) {
+        verbosity = 30;
+    }
+
+    if(NULL == sub_module) {
+        /*
+         * No valid collective module from dynamic rules
+         * nor from mca parameter
+         */
+        han_module->dynamic_errors++;
+        opal_output_verbose(verbosity, mca_coll_han_component.han_output,
+                            "coll:han:mca_coll_han_scatterv_intra_dynamic "
+                            "HAN did not find any valid module for collective %d (%s) "
+                            "with topological level %d (%s) on communicator (%s/%s). "
+                            "Please check dynamic file/mca parameters\n",
+                            SCATTERV, mca_coll_base_colltype_to_str(SCATTERV),
+                            topo_lvl, mca_coll_han_topo_lvl_to_str(topo_lvl),
+                            ompi_comm_print_cid(comm), comm->c_name);
+        OPAL_OUTPUT_VERBOSE((30, mca_coll_han_component.han_output,
+                             "HAN/SCATTERV: No module found for the sub-communicator. "
+                             "Falling back to another component\n"));
+        scatterv = han_module->previous_scatterv;
+        sub_module = han_module->previous_scatterv_module;
+    } else if (NULL == sub_module->coll_scatterv) {
+        /*
+         * No valid collective from dynamic rules
+         * nor from mca parameter
+         */
+        han_module->dynamic_errors++;
+        opal_output_verbose(verbosity, mca_coll_han_component.han_output,
+                            "coll:han:mca_coll_han_scatterv_intra_dynamic "
+                            "HAN found valid module for collective %d (%s) "
+                            "with topological level %d (%s) on communicator (%s/%s) "
+                            "but this module cannot handle this collective. "
+                            "Please check dynamic file/mca parameters\n",
+                            SCATTERV, mca_coll_base_colltype_to_str(SCATTERV),
+                            topo_lvl, mca_coll_han_topo_lvl_to_str(topo_lvl),
+                            ompi_comm_print_cid(comm), comm->c_name);
+        OPAL_OUTPUT_VERBOSE((30, mca_coll_han_component.han_output,
+                             "HAN/SCATTERV: the module found for the sub-"
+                             "communicator cannot handle the SCATTERV operation. "
+                             "Falling back to another component\n"));
+        scatterv = han_module->previous_scatterv;
+        sub_module = han_module->previous_scatterv_module;
+    } else if (GLOBAL_COMMUNICATOR == topo_lvl && sub_module == module) {
+        /*
+         * No fallback mechanism activated for this configuration
+         * sub_module is valid
+         * sub_module->coll_scatterv is valid and point to this function
+         * Call han topological collective algorithm
+         */
+        int algorithm_id = get_algorithm(SCATTERV,
+                                         MCA_COLL_HAN_ANY_MESSAGE_SIZE,
+                                         comm,
+                                         han_module);
+        scatterv = (mca_coll_base_module_scatterv_fn_t)mca_coll_han_algorithm_id_to_fn(SCATTERV, algorithm_id);
+        if (NULL == scatterv) { /* default behaviour */
+            scatterv = mca_coll_han_scatterv_intra;
+        }
+    } else {
+        /*
+         * If we get here:
+         * sub_module is valid
+         * sub_module->coll_scatterv is valid
+         * They point to the collective to use, according to the dynamic rules
+         * Selector's job is done, call the collective
+         */
+        scatterv = sub_module->coll_scatterv;
+    }
+
+    return scatterv(sbuf, scounts, displs, sdtype, 
+                    rbuf, rcount, rdtype, 
+                    root, comm, sub_module);
+}

ompi/mca/coll/han/coll_han_module.c

@@ -54,6 +54,7 @@ static void han_module_clear(mca_coll_han_module_t *han_module)
     CLEAN_PREV_COLL(han_module, gather);
     CLEAN_PREV_COLL(han_module, gatherv);
     CLEAN_PREV_COLL(han_module, scatter);
+    CLEAN_PREV_COLL(han_module, scatterv);
 
     han_module->reproducible_reduce = NULL;
     han_module->reproducible_reduce_module = NULL;
@@ -152,6 +153,7 @@ mca_coll_han_module_destruct(mca_coll_han_module_t * module)
     OBJ_RELEASE_IF_NOT_NULL(module->previous_gatherv_module);
     OBJ_RELEASE_IF_NOT_NULL(module->previous_reduce_module);
     OBJ_RELEASE_IF_NOT_NULL(module->previous_scatter_module);
+    OBJ_RELEASE_IF_NOT_NULL(module->previous_scatterv_module);
 
     han_module_clear(module);
 }
@@ -254,7 +256,7 @@ mca_coll_han_comm_query(struct ompi_communicator_t * comm, int *priority)
     han_module->super.coll_exscan     = NULL;
     han_module->super.coll_reduce_scatter = NULL;
     han_module->super.coll_scan       = NULL;
-    han_module->super.coll_scatterv   = NULL;
+    han_module->super.coll_scatterv   = mca_coll_han_scatterv_intra_dynamic;
     han_module->super.coll_barrier    = mca_coll_han_barrier_intra_dynamic;
     han_module->super.coll_scatter    = mca_coll_han_scatter_intra_dynamic;
     han_module->super.coll_reduce     = mca_coll_han_reduce_intra_dynamic;
@@ -316,6 +318,7 @@ han_module_enable(mca_coll_base_module_t * module,
     HAN_SAVE_PREV_COLL_API(gatherv);
     HAN_SAVE_PREV_COLL_API(reduce);
     HAN_SAVE_PREV_COLL_API(scatter);
+    HAN_SAVE_PREV_COLL_API(scatterv);
 
     /* set reproducible algos */
     mca_coll_han_reduce_reproducible_decision(comm, module);
@@ -332,6 +335,7 @@ han_module_enable(mca_coll_base_module_t * module,
     OBJ_RELEASE_IF_NOT_NULL(han_module->previous_gatherv_module);
     OBJ_RELEASE_IF_NOT_NULL(han_module->previous_reduce_module);
     OBJ_RELEASE_IF_NOT_NULL(han_module->previous_scatter_module);
+    OBJ_RELEASE_IF_NOT_NULL(han_module->previous_scatterv_module);
 
     return OMPI_ERROR;
 }
@@ -354,6 +358,7 @@ mca_coll_han_module_disable(mca_coll_base_module_t * module,
     OBJ_RELEASE_IF_NOT_NULL(han_module->previous_gatherv_module);
     OBJ_RELEASE_IF_NOT_NULL(han_module->previous_reduce_module);
     OBJ_RELEASE_IF_NOT_NULL(han_module->previous_scatter_module);
+    OBJ_RELEASE_IF_NOT_NULL(han_module->previous_scatterv_module);
 
     han_module_clear(han_module);