IB/hfi1: Get rid of divide in pio buffer allocator

The div instruction shows costly in profiles.

Reviewed-by: Mike Marciniszyn <mike.marciniszyn@intel.com>
Signed-off-by: Sebastian Sanchez <sebastian.sanchez@intel.com>
Signed-off-by: Dennis Dalessandro <dennis.dalessandro@intel.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>

2 files changed, 8 insertions, 4 deletions

diff --git a/drivers/infiniband/hw/hfi1/pio.c b/drivers/infiniband/hw/hfi1/pio.c
index 385e4dcf2cd3..516fac38d31e 100644
--- a/drivers/infiniband/hw/hfi1/pio.c
+++ b/drivers/infiniband/hw/hfi1/pio.c
@@ -1249,6 +1249,7 @@ int sc_enable(struct send_context *sc)
         sc->free = 0;
         sc->alloc_free = 0;
         sc->fill = 0;
+        sc->fill_wrap = 0;
         sc->sr_head = 0;
         sc->sr_tail = 0;
         sc->flags = 0;
@@ -1392,7 +1393,7 @@ struct pio_buf *sc_buffer_alloc(struct send_context *sc, u32 dw_len,
         unsigned long flags;
         unsigned long avail;
         unsigned long blocks = dwords_to_blocks(dw_len);
-        unsigned long start_fill;
+        u32 fill_wrap;
         int trycount = 0;
         u32 head, next;
 
@@ -1435,8 +1436,11 @@ retry:
         head = sc->sr_head;
 
         /* "allocate" the buffer */
-        start_fill = sc->fill;
         sc->fill += blocks;
+        fill_wrap = sc->fill_wrap;
+        sc->fill_wrap += blocks;
+        if (sc->fill_wrap >= sc->credits)
+                sc->fill_wrap = sc->fill_wrap - sc->credits;
 
         /*
          * Fill the parts that the releaser looks at before moving the head.
@@ -1465,8 +1469,7 @@ retry:
         spin_unlock_irqrestore(&sc->alloc_lock, flags);
 
         /* finish filling in the buffer outside the lock */
-        pbuf->start = sc->base_addr + ((start_fill % sc->credits)
-                                                        * PIO_BLOCK_SIZE);
+        pbuf->start = sc->base_addr + fill_wrap * PIO_BLOCK_SIZE;
         pbuf->size = sc->credits * PIO_BLOCK_SIZE;
         pbuf->end = sc->base_addr + pbuf->size;
         pbuf->block_count = blocks;
diff --git a/drivers/infiniband/hw/hfi1/pio.h b/drivers/infiniband/hw/hfi1/pio.h
index bd19507b6bb0..498b548055e0 100644
--- a/drivers/infiniband/hw/hfi1/pio.h
+++ b/drivers/infiniband/hw/hfi1/pio.h
@@ -119,6 +119,7 @@ struct send_context {
         unsigned long fill;             /* official alloc count */
         unsigned long alloc_free;       /* copy of free (less cache thrash) */
         u32 __percpu *buffers_allocated;/* count of buffers allocated */
+        u32 fill_wrap;                  /* tracks fill within ring */
         /* releaser fields */
         spinlock_t release_lock ____cacheline_aligned_in_smp;
         u32 sr_tail;                    /* shadow ring tail */