Merge pull request #7038 from jsquyres/pr/usnic-fixes-and-optimizations

btl/usnic fixes and optimizations

Author: jsquyres

opal/mca/btl/usnic/btl_usnic.h

@@ -57,7 +57,7 @@ extern uint64_t opal_btl_usnic_ticks;
 extern opal_recursive_mutex_t btl_usnic_lock;
 
 static inline uint64_t
-get_nsec(void)
+get_ticks(void)
 {
     return opal_btl_usnic_ticks;
 }
@@ -190,6 +190,14 @@ typedef struct opal_btl_usnic_component_t {
     /** retrans characteristics */
     int retrans_timeout;
 
+    /** max number of messages re-sent during a single progress
+        iteration */
+    int max_resends_per_iteration;
+
+    /** minimum number of times through component progress before
+        checking to see if standalone ACKs need to be sent */
+    int ack_iteration_delay;
+
     /** transport header length for all usNIC devices on this server
         (it is guaranteed that all usNIC devices on a single server
         will have the same underlying transport, and therefore the

opal/mca/btl/usnic/btl_usnic_component.c

@@ -380,8 +380,9 @@ static int check_usnic_config(opal_btl_usnic_module_t *module,
 
 static void usnic_clock_callback(int fd, short flags, void *timeout)
 {
-    /* 1ms == 1,000,000 ns */
-    opal_btl_usnic_ticks += 1000000;
+    /* Increase by so many ticks that we will definitely force sending
+       any ACKs that are pending */
+    opal_btl_usnic_ticks += 1000;
 
     /* run progress to make sure time change gets noticed */
     usnic_component_progress();
@@ -1128,7 +1129,7 @@ static mca_btl_base_module_t** usnic_component_init(int* num_btl_modules,
  */
 static int usnic_handle_completion(opal_btl_usnic_module_t* module,
     opal_btl_usnic_channel_t *channel, struct fi_cq_entry *completion);
-static int usnic_component_progress_2(void);
+static int usnic_component_progress_2(bool check_priority);
 static void usnic_handle_cq_error(opal_btl_usnic_module_t* module,
     opal_btl_usnic_channel_t *channel, int cq_ret);
 
@@ -1141,9 +1142,7 @@ static int usnic_component_progress(void)
     struct fi_cq_entry completion;
     opal_btl_usnic_channel_t *channel;
     static bool fastpath_ok = true;
-
-    /* update our simulated clock */
-    opal_btl_usnic_ticks += 5000;
+    bool check_priority = true;
 
     count = 0;
     if (fastpath_ok) {
@@ -1176,10 +1175,11 @@ static int usnic_component_progress(void)
                 usnic_handle_cq_error(module, channel, ret);
             }
         }
+        check_priority = false;
     }
 
     fastpath_ok = true;
-    return count + usnic_component_progress_2();
+    return count + usnic_component_progress_2(check_priority);
 }
 
 static int usnic_handle_completion(
@@ -1300,7 +1300,7 @@ usnic_handle_cq_error(opal_btl_usnic_module_t* module,
     }
 }
 
-static int usnic_component_progress_2(void)
+static int usnic_component_progress_2(bool check_priority)
 {
     int i, j, count = 0, num_events, ret;
     opal_btl_usnic_module_t* module;
@@ -1309,15 +1309,18 @@ static int usnic_component_progress_2(void)
     int rc;
     int c;
 
-    /* update our simulated clock */
-    opal_btl_usnic_ticks += 5000;
+    opal_btl_usnic_ticks += 1;
+
+    /* If we need to check priority, start with the priority channel.
+       Otherwise, just check the data channel. */
+    int c_start = check_priority ? USNIC_PRIORITY_CHANNEL : USNIC_DATA_CHANNEL;
 
     /* Poll for completions */
     for (i = 0; i < mca_btl_usnic_component.num_modules; i++) {
         module = mca_btl_usnic_component.usnic_active_modules[i];
 
         /* poll each channel */
-        for (c=0; c<USNIC_NUM_CHANNELS; ++c) {
+        for (c=c_start; c<USNIC_NUM_CHANNELS; ++c) {
             channel = &module->mod_channels[c];
 
             if (channel->chan_deferred_recv != NULL) {

opal/mca/btl/usnic/btl_usnic_frag.h

@@ -138,18 +138,24 @@ typedef struct {
        the length of the packet to meet a minimum size */
     uint16_t payload_len;
 
-    /* If this is an emulated PUT, store at this address on receiver */
-    char *put_addr;
-
     /* Type of BTL header (see enum, above) */
     uint8_t payload_type;
 
     /* true if there is piggy-backed ACK */
     uint8_t ack_present;
 
+    /* This field is ordered here so that we have no holes in the
+       struct.  Technically this doesn't matter, because we're using
+       the __packed__ attribute (so there will be no holes anyway),
+       but ordering things nicely in the struct prevents the need for
+       unaligned reads/writes when using _packed__. */
+    /* If this is an emulated PUT, store at this address on
+       receiver */
+    char *put_addr;
+
     /* tag for upper layer */
     mca_btl_base_tag_t tag;
-} opal_btl_usnic_btl_header_t;
+} __opal_attribute_packed__ opal_btl_usnic_btl_header_t;
 
 /**
  * BTL header for a chunk of a fragment

opal/mca/btl/usnic/btl_usnic_mca.c

@@ -246,9 +246,17 @@ int opal_btl_usnic_component_register(void)
     mca_btl_usnic_component.udp_port_base = (int) udp_port_base;
 
     CHECK(reg_int("retrans_timeout", "Number of microseconds before retransmitting a frame",
-                  5000, &mca_btl_usnic_component.retrans_timeout,
+                  100000, &mca_btl_usnic_component.retrans_timeout,
                   REGINT_GE_ONE, OPAL_INFO_LVL_5));
 
+    CHECK(reg_int("max_resends_per_iteration", "Maximum number of frames to resend in a single iteration through usNIC component progress",
+                  16, &mca_btl_usnic_component.max_resends_per_iteration,
+                  REGINT_GE_ONE, OPAL_INFO_LVL_5));
+
+    CHECK(reg_int("ack_iteration_delay", "Minimum number of times through usNIC \"progress\" function before checking to see if standalone ACKs need to be sent",
+                  0, &mca_btl_usnic_component.ack_iteration_delay,
+                  REGINT_GE_ZERO, OPAL_INFO_LVL_5));
+
     CHECK(reg_int("priority_limit", "Max size of \"priority\" messages (0 = use pre-set defaults; depends on number and type of devices available)",
                   0, &max_tiny_msg_size,
                   REGINT_GE_ZERO, OPAL_INFO_LVL_5));

opal/mca/btl/usnic/btl_usnic_module.c

@@ -954,11 +954,12 @@ usnic_do_resends(
     opal_btl_usnic_send_segment_t *sseg;
     opal_btl_usnic_endpoint_t *endpoint;
     struct opal_btl_usnic_channel_t *data_channel;
-    int ret;
+    int ret, count;
 
     data_channel = &module->mod_channels[USNIC_DATA_CHANNEL];
 
-    while ((get_send_credits(data_channel) > 1) &&
+    count = mca_btl_usnic_component.max_resends_per_iteration;
+    while (count > 0 && (get_send_credits(data_channel) > 1) &&
            !opal_list_is_empty(&module->pending_resend_segs)) {
 
         /*
@@ -999,6 +1000,8 @@ usnic_do_resends(
         if (OPAL_UNLIKELY(OPAL_SUCCESS != ret)) {
             opal_btl_usnic_util_abort("hotel checkin failed\n", __FILE__, __LINE__);
         }
+
+        --count;
     }
 }
 
@@ -1226,7 +1229,7 @@ opal_btl_usnic_module_progress_sends(
 
         /* Is it time to send ACK? */
         if (endpoint->endpoint_acktime == 0 ||
-            endpoint->endpoint_acktime <= get_nsec()) {
+            endpoint->endpoint_acktime <= get_ticks()) {
             if (OPAL_LIKELY(opal_btl_usnic_ack_send(module, endpoint) == OPAL_SUCCESS)) {
                 opal_btl_usnic_remove_from_endpoints_needing_ack(endpoint);
             } else {
@@ -2344,14 +2347,14 @@ static void init_freelists(opal_btl_usnic_module_t *module)
     uint32_t segsize;
 
     segsize = (module->local_modex.max_msg_size +
-           opal_cache_line_size - 1) &
+               mca_btl_usnic_component.prefix_send_offset +
+               opal_cache_line_size - 1) &
         ~(opal_cache_line_size - 1);
 
     /* Send frags freelists */
     OBJ_CONSTRUCT(&module->small_send_frags, opal_free_list_t);
     rc = usnic_compat_free_list_init(&module->small_send_frags,
-                             sizeof(opal_btl_usnic_small_send_frag_t) +
-                                 mca_btl_usnic_component.prefix_send_offset,
+                             sizeof(opal_btl_usnic_small_send_frag_t),
                              opal_cache_line_size,
                              OBJ_CLASS(opal_btl_usnic_small_send_frag_t),
                              segsize,
@@ -2368,8 +2371,7 @@ static void init_freelists(opal_btl_usnic_module_t *module)
 
     OBJ_CONSTRUCT(&module->large_send_frags, opal_free_list_t);
     rc = usnic_compat_free_list_init(&module->large_send_frags,
-                             sizeof(opal_btl_usnic_large_send_frag_t) +
-                                 mca_btl_usnic_component.prefix_send_offset,
+                             sizeof(opal_btl_usnic_large_send_frag_t),
                              opal_cache_line_size,
                              OBJ_CLASS(opal_btl_usnic_large_send_frag_t),
                              0,  /* payload size */
@@ -2386,8 +2388,7 @@ static void init_freelists(opal_btl_usnic_module_t *module)
 
     OBJ_CONSTRUCT(&module->put_dest_frags, opal_free_list_t);
     rc = usnic_compat_free_list_init(&module->put_dest_frags,
-                             sizeof(opal_btl_usnic_put_dest_frag_t) +
-                                 mca_btl_usnic_component.prefix_send_offset,
+                             sizeof(opal_btl_usnic_put_dest_frag_t),
                              opal_cache_line_size,
                              OBJ_CLASS(opal_btl_usnic_put_dest_frag_t),
                              0,  /* payload size */
@@ -2405,8 +2406,7 @@ static void init_freelists(opal_btl_usnic_module_t *module)
     /* list of segments to use for sending */
     OBJ_CONSTRUCT(&module->chunk_segs, opal_free_list_t);
     rc = usnic_compat_free_list_init(&module->chunk_segs,
-                             sizeof(opal_btl_usnic_chunk_segment_t) +
-                                 mca_btl_usnic_component.prefix_send_offset,
+                             sizeof(opal_btl_usnic_chunk_segment_t),
                              opal_cache_line_size,
                              OBJ_CLASS(opal_btl_usnic_chunk_segment_t),
                              segsize,
@@ -2424,11 +2424,11 @@ static void init_freelists(opal_btl_usnic_module_t *module)
     /* ACK segments freelist */
     uint32_t ack_segment_len;
     ack_segment_len = (sizeof(opal_btl_usnic_btl_header_t) +
+                       mca_btl_usnic_component.prefix_send_offset +
             opal_cache_line_size - 1) & ~(opal_cache_line_size - 1);
     OBJ_CONSTRUCT(&module->ack_segs, opal_free_list_t);
     rc = usnic_compat_free_list_init(&module->ack_segs,
-                             sizeof(opal_btl_usnic_ack_segment_t) +
-                                 mca_btl_usnic_component.prefix_send_offset,
+                             sizeof(opal_btl_usnic_ack_segment_t),
                              opal_cache_line_size,
                              OBJ_CLASS(opal_btl_usnic_ack_segment_t),
                              ack_segment_len,

opal/mca/btl/usnic/btl_usnic_recv.h

@@ -112,9 +112,12 @@ opal_btl_usnic_update_window(
         opal_btl_usnic_add_to_endpoints_needing_ack(endpoint);
     }
 
-    /* give this process a chance to send something before ACKing */
+    /* A hueristic: set to send this ACK after we have checked our
+       incoming DATA_CHANNEL component.act_iteration_delay times
+       (i.e., so we can piggyback an ACK on an outgoing send) */
     if (0 == endpoint->endpoint_acktime) {
-        endpoint->endpoint_acktime = get_nsec() + 50000;    /* 50 usec */
+        endpoint->endpoint_acktime =
+            get_ticks() + mca_btl_usnic_component.ack_iteration_delay;
     }
 
     /* Save this incoming segment in the received segmentss array on the