UCT/TCP: Increase keepalive interval from 1 to 2 seconds and use system default for keepalive retries count [v1.11.x]

NEWS

@@ -168,6 +168,7 @@
 * Fixes in reachability of loopback ifaces
 * Fixes addressing  possible uninitialized memory accesses
 * Fixes in error flow for endpoints created upon receiving connection request
+* Fixes in TCP keepalive to avoid false-positive error detection
 #### UCM
 * Fixes addressing heap corruption caused by ucp_set_event_handler()
 * Fixes in mmap events test

src/uct/tcp/tcp.h

@@ -65,7 +65,7 @@
 #define UCT_TCP_EP_DEFAULT_KEEPALIVE_IDLE    10
 
 /* The seconds between individual keepalive probes */
-#define UCT_TCP_EP_DEFAULT_KEEPALIVE_INTVL   1
+#define UCT_TCP_EP_DEFAULT_KEEPALIVE_INTVL   2
 
 
 /**
@@ -402,7 +402,7 @@ typedef struct uct_tcp_iface {
             ucs_time_t            idle;              /* The time the connection needs to remain
                                                       * idle before TCP starts sending keepalive
                                                       * probes (TCP_KEEPIDLE socket option) */
-            unsigned              cnt;               /* The maximum number of keepalive probes TCP
+            unsigned long         cnt;               /* The maximum number of keepalive probes TCP
                                                       * should send before dropping the connection
                                                       * (TCP_KEEPCNT socket option). */
             ucs_time_t            intvl;             /* The time between individual keepalive
@@ -440,7 +440,7 @@ typedef struct uct_tcp_iface_config {
     ucs_range_spec_t               port_range;
     struct {
         ucs_time_t                 idle;
-        unsigned                   cnt;
+        unsigned long              cnt;
         ucs_time_t                 intvl;
     } keepalive;
 } uct_tcp_iface_config_t;

src/uct/tcp/tcp_ep.c

@@ -492,13 +492,16 @@ static inline void uct_tcp_ep_ctx_move(uct_tcp_ep_ctx_t *to_ctx,
     memset(from_ctx, 0, sizeof(*from_ctx));
 }
 
-static int uct_tcp_ep_time_seconds(ucs_time_t time_val, int auto_val)
+static int uct_tcp_ep_time_seconds(ucs_time_t time_val, int auto_val,
+                                   int max_val)
 {
     if (time_val == UCS_TIME_AUTO) {
         return auto_val;
+    } else if (time_val == UCS_TIME_INFINITY) {
+        return max_val;
     }
 
-    return ucs_max(1, (int)ucs_time_to_sec(time_val));
+    return ucs_min(max_val, ucs_max(1l, ucs_time_to_sec(time_val)));
 }
 
 static ucs_status_t uct_tcp_ep_keepalive_enable(uct_tcp_ep_t *ep)
@@ -509,28 +512,38 @@ static ucs_status_t uct_tcp_ep_keepalive_enable(uct_tcp_ep_t *ep)
     const int optval       = 1;
     int idle_sec;
     int intvl_sec;
+    int keepalive_cnt;
     ucs_status_t status;
 
     if (!uct_tcp_keepalive_is_enabled(iface)) {
         return UCS_OK;
     }
 
     idle_sec  = uct_tcp_ep_time_seconds(iface->config.keepalive.idle,
-                                        UCT_TCP_EP_DEFAULT_KEEPALIVE_IDLE);
+                                        UCT_TCP_EP_DEFAULT_KEEPALIVE_IDLE,
+                                        INT16_MAX);
     intvl_sec = uct_tcp_ep_time_seconds(iface->config.keepalive.intvl,
-                                        UCT_TCP_EP_DEFAULT_KEEPALIVE_INTVL);
+                                        UCT_TCP_EP_DEFAULT_KEEPALIVE_INTVL,
+                                        INT16_MAX);
 
     status = ucs_socket_setopt(ep->fd, IPPROTO_TCP, TCP_KEEPINTVL,
                                &intvl_sec, sizeof(intvl_sec));
     if (status != UCS_OK) {
         return status;
     }
 
-    status = ucs_socket_setopt(ep->fd, IPPROTO_TCP, TCP_KEEPCNT,
-                               &iface->config.keepalive.cnt,
-                               sizeof(iface->config.keepalive.cnt));
-    if (status != UCS_OK) {
-        return status;
+    if (iface->config.keepalive.cnt != UCS_ULUNITS_AUTO) {
+        if (iface->config.keepalive.cnt == UCS_ULUNITS_INF) {
+            keepalive_cnt = INT8_MAX;
+        } else {
+            keepalive_cnt = ucs_min(INT8_MAX, iface->config.keepalive.cnt);
+        }
+
+        status = ucs_socket_setopt(ep->fd, IPPROTO_TCP, TCP_KEEPCNT,
+                                   &keepalive_cnt, sizeof(keepalive_cnt));
+        if (status != UCS_OK) {
+            return status;
+        }
     }
 
     status = ucs_socket_setopt(ep->fd, IPPROTO_TCP, TCP_KEEPIDLE,

src/uct/tcp/tcp_iface.c

@@ -89,18 +89,19 @@ static ucs_config_field_t uct_tcp_iface_config_table[] = {
 #ifdef UCT_TCP_EP_KEEPALIVE
   {"KEEPIDLE", UCS_PP_MAKE_STRING(UCT_TCP_EP_DEFAULT_KEEPALIVE_IDLE) "s",
    "The time the connection needs to remain idle before TCP starts sending "
-   "keepalive probes.",
+   "keepalive probes. Specifying \"inf\" disables keepalive.",
    ucs_offsetof(uct_tcp_iface_config_t, keepalive.idle),
                 UCS_CONFIG_TYPE_TIME_UNITS},
 
-  {"KEEPCNT", "3",
+  {"KEEPCNT", "auto",
    "The maximum number of keepalive probes TCP should send before "
-   "dropping the connection.",
+   "dropping the connection. Specifying \"inf\" disables keepalive.",
    ucs_offsetof(uct_tcp_iface_config_t, keepalive.cnt),
-                UCS_CONFIG_TYPE_UINT},
+                UCS_CONFIG_TYPE_ULUNITS},
 
   {"KEEPINTVL", UCS_PP_MAKE_STRING(UCT_TCP_EP_DEFAULT_KEEPALIVE_INTVL) "s",
-   "The time between individual keepalive probes.",
+   "The time between individual keepalive probes. Specifying \"inf\" disables"
+   " keepalive.",
    ucs_offsetof(uct_tcp_iface_config_t, keepalive.intvl),
                 UCS_CONFIG_TYPE_TIME_UNITS},
 #endif /* UCT_TCP_EP_KEEPALIVE */
@@ -872,7 +873,7 @@ int uct_tcp_keepalive_is_enabled(uct_tcp_iface_t *iface)
 {
 #ifdef UCT_TCP_EP_KEEPALIVE
     return (iface->config.keepalive.idle != UCS_TIME_INFINITY) &&
-           (iface->config.keepalive.cnt != 0) &&
+           (iface->config.keepalive.cnt != UCS_ULUNITS_INF) &&
            (iface->config.keepalive.intvl != UCS_TIME_INFINITY);
 #else /* UCT_TCP_EP_KEEPALIVE */
     return 0;