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vmbus: replace modulus operation with subtraction 

Takes less clock cycles to check for ring wrap and subtract than to
do a modulus instruction.

Signed-off-by: Stephen Hemminger <sthemmin@microsoft.com>
Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Stephen Hemminger 2017-02-11 23:02:25 -07:00 committed by Greg Kroah-Hartman
parent e4165a0fad
commit 8d12f88257
1 changed files with 6 additions and 3 deletions
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9
drivers/hv/ring_buffer.c
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@ -112,7 +112,8 @@ hv_get_next_readlocation_withoffset(const struct hv_ring_buffer_info *ring_info,
u32 next = ring_info->ring_buffer->read_index;
next += offset;
next %= ring_info->ring_datasize;
if (next >= ring_info->ring_datasize)
next -= ring_info->ring_datasize;
return next;
}
@ -156,7 +157,8 @@ static u32 hv_copyfrom_ringbuffer(
memcpy(dest, ring_buffer + start_read_offset, destlen);
start_read_offset += destlen;
start_read_offset %= ring_buffer_size;
if (start_read_offset >= ring_buffer_size)
start_read_offset -= ring_buffer_size;
return start_read_offset;
}
@ -178,7 +180,8 @@ static u32 hv_copyto_ringbuffer(
memcpy(ring_buffer + start_write_offset, src, srclen);
start_write_offset += srclen;
start_write_offset %= ring_buffer_size;
if (start_write_offset >= ring_buffer_size)
start_write_offset -= ring_buffer_size;
return start_write_offset;
}