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

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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>
This commit is contained in:
Sebastian Sanchez 2016-10-25 13:12:28 -07:00 committed by Doug Ledford
parent fe4d924396
commit 2474d775d9
2 changed files with 8 additions and 4 deletions
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11
drivers/infiniband/hw/hfi1/pio.c
View File

@ -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;

1
drivers/infiniband/hw/hfi1/pio.h
View File

@ -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 */