LU-9448 lnet: handle empty CPTs

Make the LND code handle empty CPTs.

If a scheduler is associated with an empty CPT it will have no
threads created. If a NID hashes to that CPT, then pick the
next scheduler which does have at least 1 started thread.
Associate the connection with the CPT of the selected scheduler

Test-Parameters: trivial
Signed-off-by: Amir Shehata <amir.shehata@intel.com>
Change-Id: I8ed83f295fe9852537d4bb063a4d8271c6a45c2c
Reviewed-on: https://review.whamcloud.com/27145
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Doug Oucharek <doug.s.oucharek@intel.com>
Reviewed-by: Dmitry Eremin <dmitry.eremin@intel.com>
Reviewed-by: Olaf Weber <olaf.weber@hpe.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>

diff --git a/lnet/klnds/o2iblnd/o2iblnd.c b/lnet/klnds/o2iblnd/o2iblnd.c
index 70ed74f..12dade5 100644 (file)
--- a/lnet/klnds/o2iblnd/o2iblnd.c
+++ b/lnet/klnds/o2iblnd/o2iblnd.c
@@ -698,6 +698,36 @@ kiblnd_get_completion_vector(kib_conn_t *conn, int cpt)
        return 1;
 }
 
+/*
+ * Get the scheduler bound to this CPT. If the scheduler has no
+ * threads, which means that the CPT has no CPUs, then grab the
+ * next scheduler that we can use.
+ *
+ * This case would be triggered if a NUMA node is configured with
+ * no associated CPUs.
+ */
+static struct kib_sched_info *
+kiblnd_get_scheduler(int cpt)
+{
+       struct kib_sched_info *sched;
+       int i;
+
+       sched = kiblnd_data.kib_scheds[cpt];
+
+       if (sched->ibs_nthreads > 0)
+               return sched;
+
+       cfs_percpt_for_each(sched, i, kiblnd_data.kib_scheds) {
+               if (sched->ibs_nthreads > 0) {
+                       CDEBUG(D_NET, "scheduler[%d] has no threads. selected scheduler[%d]\n",
+                                       cpt, sched->ibs_cpt);
+                       return sched;
+               }
+       }
+
+       return NULL;
+}
+
 kib_conn_t *
 kiblnd_create_conn(kib_peer_ni_t *peer_ni, struct rdma_cm_id *cmid,
                   int state, int version)
@@ -730,9 +760,18 @@ kiblnd_create_conn(kib_peer_ni_t *peer_ni, struct rdma_cm_id *cmid,
        dev = net->ibn_dev;
 
        cpt = lnet_cpt_of_nid(peer_ni->ibp_nid, peer_ni->ibp_ni);
-       sched = kiblnd_data.kib_scheds[cpt];
+       sched = kiblnd_get_scheduler(cpt);
+
+       if (sched == NULL) {
+               CERROR("no schedulers available. node is unhealthy\n");
+               goto failed_0;
+       }
 
-       LASSERT(sched->ibs_nthreads > 0);
+       /*
+        * The cpt might have changed if we ended up selecting a non cpt
+        * native scheduler. So use the scheduler's cpt instead.
+        */
+       cpt = sched->ibs_cpt;
 
        LIBCFS_CPT_ALLOC(init_qp_attr, lnet_cpt_table(), cpt,
                         sizeof(*init_qp_attr));

diff --git a/lnet/klnds/socklnd/socklnd.c b/lnet/klnds/socklnd/socklnd.c
index 0852e85..0fdedba 100644 (file)
--- a/lnet/klnds/socklnd/socklnd.c
+++ b/lnet/klnds/socklnd/socklnd.c
@@ -670,8 +670,18 @@ ksocknal_choose_scheduler_locked(unsigned int cpt)
        ksock_sched_t           *sched;
        int                     i;
 
-       LASSERT(info->ksi_nthreads > 0);
+       if (info->ksi_nthreads == 0) {
+               cfs_percpt_for_each(info, i, ksocknal_data.ksnd_sched_info) {
+                       if (info->ksi_nthreads > 0) {
+                               CDEBUG(D_NET, "scheduler[%d] has no threads. selected scheduler[%d]\n",
+                                      cpt, info->ksi_cpt);
+                               goto select_sched;
+                       }
+               }
+               return NULL;
+       }
 
+select_sched:
        sched = &info->ksi_scheds[0];
        /*
         * NB: it's safe so far, but info->ksi_nthreads could be changed
@@ -1263,6 +1273,15 @@ ksocknal_create_conn(struct lnet_ni *ni, ksock_route_t *route,
        peer_ni->ksnp_error = 0;
 
        sched = ksocknal_choose_scheduler_locked(cpt);
+       if (!sched) {
+               CERROR("no schedulers available. node is unhealthy\n");
+               goto failed_2;
+       }
+       /*
+        * The cpt might have changed if we ended up selecting a non cpt
+        * native scheduler. So use the scheduler's cpt instead.
+        */
+       cpt = sched->kss_info->ksi_cpt;
         sched->kss_nconns++;
         conn->ksnc_scheduler = sched;
 
@@ -2425,20 +2444,23 @@ ksocknal_base_startup(void)
                info->ksi_nthreads_max = nthrs;
                info->ksi_cpt = i;
 
-               LIBCFS_CPT_ALLOC(info->ksi_scheds, lnet_cpt_table(), i,
-                                info->ksi_nthreads_max * sizeof(*sched));
-               if (info->ksi_scheds == NULL)
-                       goto failed;
-
-               for (; nthrs > 0; nthrs--) {
-                       sched = &info->ksi_scheds[nthrs - 1];
-
-                       sched->kss_info = info;
-                       spin_lock_init(&sched->kss_lock);
-                       INIT_LIST_HEAD(&sched->kss_rx_conns);
-                       INIT_LIST_HEAD(&sched->kss_tx_conns);
-                       INIT_LIST_HEAD(&sched->kss_zombie_noop_txs);
-                       init_waitqueue_head(&sched->kss_waitq);
+               if (nthrs != 0) {
+                       LIBCFS_CPT_ALLOC(info->ksi_scheds, lnet_cpt_table(), i,
+                                        info->ksi_nthreads_max *
+                                               sizeof(*sched));
+                       if (info->ksi_scheds == NULL)
+                               goto failed;
+
+                       for (; nthrs > 0; nthrs--) {
+                               sched = &info->ksi_scheds[nthrs - 1];
+
+                               sched->kss_info = info;
+                               spin_lock_init(&sched->kss_lock);
+                               INIT_LIST_HEAD(&sched->kss_rx_conns);
+                               INIT_LIST_HEAD(&sched->kss_tx_conns);
+                               INIT_LIST_HEAD(&sched->kss_zombie_noop_txs);
+                               init_waitqueue_head(&sched->kss_waitq);
+                       }
                }
         }