cxgb3: ring rx door bell less frequently

Ring free lists door bell less frequently,
specifically every quarter of the active FL
size.

Signed-off-by: Divy Le Ray <divy@chelsio.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 25 insertions, 8 deletions

diff --git a/drivers/net/cxgb3/adapter.h b/drivers/net/cxgb3/adapter.h
index fbe15699584..95dce483247 100644
--- a/drivers/net/cxgb3/adapter.h
+++ b/drivers/net/cxgb3/adapter.h
@@ -91,6 +91,7 @@ struct rx_sw_desc;
 struct sge_fl {                     /* SGE per free-buffer list state */
         unsigned int buf_size;      /* size of each Rx buffer */
         unsigned int credits;       /* # of available Rx buffers */
+        unsigned int pend_cred;     /* new buffers since last FL DB ring */
         unsigned int size;          /* capacity of free list */
         unsigned int cidx;          /* consumer index */
         unsigned int pidx;          /* producer index */
diff --git a/drivers/net/cxgb3/sge.c b/drivers/net/cxgb3/sge.c
index 8205aa4ae94..882beafeb74 100644
--- a/drivers/net/cxgb3/sge.c
+++ b/drivers/net/cxgb3/sge.c
@@ -63,6 +63,10 @@
 #define SGE_RX_DROP_THRES 16
 
 /*
+ * Max number of Rx buffers we replenish at a time.
+ */
+#define MAX_RX_REFILL 16U
+/*
  * Period of the Tx buffer reclaim timer.  This timer does not need to run
  * frequently as Tx buffers are usually reclaimed by new Tx packets.
  */
@@ -423,6 +427,14 @@ static int alloc_pg_chunk(struct sge_fl *q, struct rx_sw_desc *sd, gfp_t gfp,
         return 0;
 }
 
+static inline void ring_fl_db(struct adapter *adap, struct sge_fl *q)
+{
+        if (q->pend_cred >= q->credits / 4) {
+                q->pend_cred = 0;
+                t3_write_reg(adap, A_SG_KDOORBELL, V_EGRCNTX(q->cntxt_id));
+        }
+}
+
 /**
  *      refill_fl - refill an SGE free-buffer list
  *      @adapter: the adapter
@@ -478,19 +490,19 @@ nomem:				q->alloc_failed++;
                         sd = q->sdesc;
                         d = q->desc;
                 }
-                q->credits++;
                 count++;
         }
-        wmb();
-        if (likely(count))
-                t3_write_reg(adap, A_SG_KDOORBELL, V_EGRCNTX(q->cntxt_id));
+
+        q->credits += count;
+        q->pend_cred += count;
+        ring_fl_db(adap, q);
 
         return count;
 }
 
 static inline void __refill_fl(struct adapter *adap, struct sge_fl *fl)
 {
-        refill_fl(adap, fl, min(16U, fl->size - fl->credits),
+        refill_fl(adap, fl, min(MAX_RX_REFILL, fl->size - fl->credits),
                   GFP_ATOMIC | __GFP_COMP);
 }
 
@@ -515,13 +527,15 @@ static void recycle_rx_buf(struct adapter *adap, struct sge_fl *q,
         wmb();
         to->len_gen = cpu_to_be32(V_FLD_GEN1(q->gen));
         to->gen2 = cpu_to_be32(V_FLD_GEN2(q->gen));
-        q->credits++;
 
         if (++q->pidx == q->size) {
                 q->pidx = 0;
                 q->gen ^= 1;
         }
-        t3_write_reg(adap, A_SG_KDOORBELL, V_EGRCNTX(q->cntxt_id));
+
+        q->credits++;
+        q->pend_cred++;
+        ring_fl_db(adap, q);
 }
 
 /**
@@ -732,7 +746,9 @@ recycle:
                 return skb;
         }
 
-        if (unlikely(fl->credits < drop_thres))
+        if (unlikely(fl->credits < drop_thres) &&
+            refill_fl(adap, fl, min(MAX_RX_REFILL, fl->size - fl->credits - 1),
+                      GFP_ATOMIC | __GFP_COMP) == 0)
                 goto recycle;
 
 use_orig_buf: