gossip: update stem burst

Author: ravyu-jump

src/app/firedancer-dev/commands/gossip.c

@@ -86,7 +86,7 @@ gossip_cmd_topo( config_t * config ) {
   }
 
   fd_topob_wksp( topo, "gossip_net" );
-  fd_topob_link( topo, "gossip_net", "gossip_net", config->net.ingress_buffer_size, FD_NET_MTU, 1UL );
+  fd_topob_link( topo, "gossip_net", "gossip_net", 65536*4UL, FD_NET_MTU, 1UL );
   fd_topos_tile_in_net( topo, "metric_in", "gossip_net", 0UL, FD_TOPOB_UNRELIABLE, FD_TOPOB_POLLED );
   fd_topob_tile_out( topo, "gossip", 0UL, "gossip_net", 0UL );
 
@@ -115,13 +115,13 @@ gossip_cmd_topo( config_t * config ) {
   fd_topob_wksp( topo, "gossip_gossv" );
   fd_topob_wksp( topo, "gossip_out" );
 
-  fd_topob_link(     topo, "gossip_gossv", "gossip_gossv", 4096UL, sizeof(fd_gossip_ping_update_t), 1UL );
+  fd_topob_link(     topo, "gossip_gossv", "gossip_gossv", 65536UL*4, sizeof(fd_gossip_ping_update_t), 1UL );
   fd_topob_tile_out( topo, "gossip", 0UL, "gossip_gossv", 0UL );
 
-  fd_topob_link( topo, "gossip_out", "gossip_out", 65536UL, sizeof(fd_gossip_update_message_t), 1UL );
+  fd_topob_link( topo, "gossip_out", "gossip_out", 65536UL*4, sizeof(fd_gossip_update_message_t), 1UL );
   fd_topob_tile_out( topo, "gossip", 0UL, "gossip_out", 0UL );
   for( ulong i=0UL; i<gossvf_tile_count; i++ ) {
-    fd_topob_link(     topo, "gossvf_gossi", "gossvf_gossi", config->net.ingress_buffer_size, sizeof(fd_gossip_view_t)+FD_NET_MTU, 1UL );
+    fd_topob_link(     topo, "gossvf_gossi", "gossvf_gossi", 65536UL*4, sizeof(fd_gossip_view_t)+FD_NET_MTU, 1UL );
     fd_topob_tile_out( topo, "gossvf", i, "gossvf_gossi", i );
     fd_topob_tile_in(  topo, "gossip", 0UL, "metric_in", "gossvf_gossi", i, FD_TOPOB_RELIABLE, FD_TOPOB_POLLED );
 

src/discof/gossip/fd_gossip_tile.c

@@ -493,8 +493,47 @@ populate_allowed_fds( fd_topo_t const *      topo,
   return out_cnt;
 }
 
-/* TODO: Size for the worst case ... 16k contact info updates + max crds in a pull request or push, all generating a frag */
-#define STEM_BURST (1<<5)
+/* Account for worst case in fd_gossip_rx and fd_gossip_advance, which
+   are both called in returnable_frag.
+
+   fd_gossip_rx: Gossip updates are sent out via the gossip_out link for
+    specific CRDS messages received, and when a contact info is dropped.
+    Worst case is when:
+    - all incoming CRDS messages are broadcasted as updates, and
+    - CRDS table is full, and all entries dropped to make way for new
+      ones are contact infos
+
+    Ping tracker track also publishes a status change on the
+    gossip_gossv link if an incoming pong changes an inactive or
+    unpinged peer to active. There is only one pong processed per
+    after_frag loop.
+
+    This leaves us with a worst case of FD_GOSSIP_MSG_MAX_CRDS*2 on
+    gossip_out, and 1 on gossip_gossv.
+
+   fd_gossip_advance: two links we need to look at: the gossip_gossv
+    link that publishes fd_ping_tracker changes and the gossip_out link
+    for when contact infos are dropped during expiry.
+
+    fd_ping_tracker publishes a ping status change message when a peer
+     becomes inactive. In the worst case, all peers can become inactive
+     in one loop. So there would be FD_PING_TRACKER_MAX ping status
+     changes.
+
+    During the expire loop, all contact infos might be dropped in one
+    iteration, which would result in CRDS_MAX_CONTACT_INFO gossip
+    updates
+
+   We find the worst case burst by taking the maximum burst of the two
+   links in fd_gossip_rx and fd_gossip_advance. That would be:
+                        gossip_out link                    gossip_gossv link
+   max( FD_GOSSIP_MSG_CRDS_MAX*2+CRDS_MAX_CONTACT_INFO, 1+FD_PING_TRACKER_MAX)
+
+   */
+
+FD_STATIC_ASSERT( CRDS_MAX_CONTACT_INFO+FD_GOSSIP_MSG_MAX_CRDS*2UL<=FD_PING_TRACKER_MAX+1UL,
+                  "Gossip stem burst needs recalculating" );
+#define STEM_BURST ( FD_PING_TRACKER_MAX+1UL )
 
 #define STEM_LAZY  (128L*3000L)