LU-6122 lnet: Allocate the correct number of rtr buffers

This patch ensures that the correct number of router buffers are
allocated.  It keeps a count that keeps track of the number of
buffers allocated.  Another count keeps the number of buffers
requested. The number of buffers allocated is set when creating
new buffers and reduced when buffers are freed.

The number of requested buffer is set when the buffers are
allocated and is checked when credits are returned to determine
whether the buffer should be freed or kept.

In lnet_rtrpool_adjust_bufs() grab lnet_net_lock() before using
rbp_nbuffers to ensure that it doesn't change by
lnet_return_rx_credits_locked() during the process of allocating
new buffers.  All other access to rbp_nbuffers is already being
protected by lnet_net_lock().

This avoids the case where we allocate less than the desired
number of buffers.

Signed-off-by: Amir Shehata <amir.shehata@intel.com>
Change-Id: I96627cc8ba3d3d70a0bf581b21ccd3c9b2de327f
Reviewed-on: http://review.whamcloud.com/13519
Tested-by: Jenkins
Reviewed-by: Jinshan Xiong <jinshan.xiong@intel.com>
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Doug Oucharek <doug.s.oucharek@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>

diff --git a/lnet/include/lnet/lib-types.h b/lnet/include/lnet/lib-types.h
index 4701b38..5a63cd5 100644 (file)
--- a/lnet/include/lnet/lib-types.h
+++ b/lnet/include/lnet/lib-types.h
@@ -431,7 +431,9 @@ typedef struct {
        struct list_head        rbp_msgs;
        /* # pages in each buffer */
        int                     rbp_npages;
        struct list_head        rbp_msgs;
        /* # pages in each buffer */
        int                     rbp_npages;

-       /* # buffers */
+       /* requested number of buffers */
+       int                     rbp_req_nbuffers;
+       /* # buffers actually allocated */

        int                     rbp_nbuffers;
        /* # free buffers / blocked messages */
        int                     rbp_credits;
        int                     rbp_nbuffers;
        /* # free buffers / blocked messages */
        int                     rbp_credits;

diff --git a/lnet/lnet/lib-move.c b/lnet/lnet/lib-move.c
index e53370f..6d3a31e 100644 (file)
--- a/lnet/lnet/lib-move.c
+++ b/lnet/lnet/lib-move.c
@@ -1095,9 +1095,11 @@ lnet_return_rx_credits_locked(lnet_msg_t *msg)
                /* It is possible that a user has lowered the desired number of
                 * buffers in this pool.  Make sure we never put back
                 * more buffers than the stated number. */
                /* It is possible that a user has lowered the desired number of
                 * buffers in this pool.  Make sure we never put back
                 * more buffers than the stated number. */

-               if (rbp->rbp_credits >= rbp->rbp_nbuffers) {
-                       /* Discard this buffer so we don't have too many. */
+               if (unlikely(rbp->rbp_credits >= rbp->rbp_req_nbuffers)) {
+                       /* Discard this buffer so we don't have too
+                        * many. */

                        lnet_destroy_rtrbuf(rb, rbp->rbp_npages);
                        lnet_destroy_rtrbuf(rb, rbp->rbp_npages);

+                       rbp->rbp_nbuffers--;

                } else {
                        list_add(&rb->rb_list, &rbp->rbp_bufs);
                        rbp->rbp_credits++;
                } else {
                        list_add(&rb->rb_list, &rbp->rbp_bufs);
                        rbp->rbp_credits++;

diff --git a/lnet/lnet/router.c b/lnet/lnet/router.c
index 6699245..e7eb4c9 100644 (file)
--- a/lnet/lnet/router.c
+++ b/lnet/lnet/router.c
@@ -1361,6 +1361,7 @@ lnet_rtrpool_free_bufs(lnet_rtrbufpool_t *rbp, int cpt)
        lnet_net_lock(cpt);
        lnet_drop_routed_msgs_locked(&rbp->rbp_msgs, cpt);
        list_splice_init(&rbp->rbp_bufs, &tmp);
        lnet_net_lock(cpt);
        lnet_drop_routed_msgs_locked(&rbp->rbp_msgs, cpt);
        list_splice_init(&rbp->rbp_bufs, &tmp);

+       rbp->rbp_req_nbuffers = 0;

        rbp->rbp_nbuffers = rbp->rbp_credits = 0;
        rbp->rbp_mincredits = 0;
        lnet_net_unlock(cpt);
        rbp->rbp_nbuffers = rbp->rbp_credits = 0;
        rbp->rbp_mincredits = 0;
        lnet_net_unlock(cpt);


@@ -1380,37 +1381,50 @@ lnet_rtrpool_adjust_bufs(lnet_rtrbufpool_t *rbp, int nbufs, int cpt)
        lnet_rtrbuf_t   *rb;
        int             num_rb;
        int             num_buffers = 0;
        lnet_rtrbuf_t   *rb;
        int             num_rb;
        int             num_buffers = 0;

+       int             old_req_nbufs;

        int             npages = rbp->rbp_npages;
 
        int             npages = rbp->rbp_npages;
 

+       lnet_net_lock(cpt);

        /* If we are called for less buffers than already in the pool, we
        /* If we are called for less buffers than already in the pool, we

-        * just lower the nbuffers number and excess buffers will be
+        * just lower the req_nbuffers number and excess buffers will be

         * thrown away as they are returned to the free list.  Credits
         * thrown away as they are returned to the free list.  Credits

-        * then get adjusted as well. */
-       if (nbufs <= rbp->rbp_nbuffers) {
-               lnet_net_lock(cpt);
-               rbp->rbp_nbuffers = nbufs;
+        * then get adjusted as well.
+        * If we already have enough buffers allocated to serve the
+        * increase requested, then we can treat that the same way as we
+        * do the decrease. */
+       num_rb = nbufs - rbp->rbp_nbuffers;
+       if (nbufs <= rbp->rbp_req_nbuffers || num_rb <= 0) {
+               rbp->rbp_req_nbuffers = nbufs;

                lnet_net_unlock(cpt);
                return 0;
        }
                lnet_net_unlock(cpt);
                return 0;
        }

+       /* store the older value of rbp_req_nbuffers and then set it to
+        * the new request to prevent lnet_return_rx_credits_locked() from
+        * freeing buffers that we need to keep around */
+       old_req_nbufs = rbp->rbp_req_nbuffers;
+       rbp->rbp_req_nbuffers = nbufs;
+       lnet_net_unlock(cpt);

 
        INIT_LIST_HEAD(&rb_list);
 
        /* allocate the buffers on a local list first.  If all buffers are
         * allocated successfully then join this list to the rbp buffer
         * list.  If not then free all allocated buffers. */
 
        INIT_LIST_HEAD(&rb_list);
 
        /* allocate the buffers on a local list first.  If all buffers are
         * allocated successfully then join this list to the rbp buffer
         * list.  If not then free all allocated buffers. */

-       num_rb = rbp->rbp_nbuffers;
-
-       while (num_rb < nbufs) {
+       while (num_rb-- > 0) {

                rb = lnet_new_rtrbuf(rbp, cpt);
                if (rb == NULL) {
                        CERROR("Failed to allocate %d route bufs of %d pages\n",
                               nbufs, npages);
                rb = lnet_new_rtrbuf(rbp, cpt);
                if (rb == NULL) {
                        CERROR("Failed to allocate %d route bufs of %d pages\n",
                               nbufs, npages);

+
+                       lnet_net_lock(cpt);
+                       rbp->rbp_req_nbuffers = old_req_nbufs;
+                       lnet_net_unlock(cpt);
+

                        goto failed;
                }
 
                list_add(&rb->rb_list, &rb_list);
                num_buffers++;
                        goto failed;
                }
 
                list_add(&rb->rb_list, &rb_list);
                num_buffers++;

-               num_rb++;

        }
 
        lnet_net_lock(cpt);
        }
 
        lnet_net_lock(cpt);


@@ -1445,9 +1459,9 @@ lnet_rtrpool_init(lnet_rtrbufpool_t *rbp, int npages)
        INIT_LIST_HEAD(&rbp->rbp_msgs);
        INIT_LIST_HEAD(&rbp->rbp_bufs);
 
        INIT_LIST_HEAD(&rbp->rbp_msgs);
        INIT_LIST_HEAD(&rbp->rbp_bufs);
 

-        rbp->rbp_npages = npages;
-        rbp->rbp_credits = 0;
-        rbp->rbp_mincredits = 0;
+       rbp->rbp_npages = npages;
+       rbp->rbp_credits = 0;
+       rbp->rbp_mincredits = 0;

 }
 
 void
 }
 
 void