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Commit 2474d775 authored by Sebastian Sanchez's avatar Sebastian Sanchez Committed by Doug Ledford
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IB/hfi1: Get rid of divide in pio buffer allocator 



The div instruction shows costly in profiles.

Reviewed-by: default avatarMike Marciniszyn <mike.marciniszyn@intel.com>
Signed-off-by: default avatarSebastian Sanchez <sebastian.sanchez@intel.com>
Signed-off-by: default avatarDennis Dalessandro <dennis.dalessandro@intel.com>
Signed-off-by: default avatarDoug Ledford <dledford@redhat.com>
parent fe4d9243

drivers/infiniband/hw/hfi1/pio.c

+7 −4
Original line number Diff line number Diff line
@@ -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 @@ struct pio_buf *sc_buffer_alloc(struct send_context *sc, u32 dw_len, 
	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 @@ struct pio_buf *sc_buffer_alloc(struct send_context *sc, u32 dw_len, 
	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;

drivers/infiniband/hw/hfi1/pio.h

+1 −0
Original line number Diff line number Diff line
@@ -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 */