From: Long Li <longli@xxxxxxxxxxxxx> The ring buffer code uses %= to calculate index. For x86/64, %= compiles to div, more than 10 times slower than sub. Replace div with sub for this data heavy code path. Signed-off-by: Long Li <longli@xxxxxxxxxxxxx> --- drivers/hv/ring_buffer.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) diff --git a/drivers/hv/ring_buffer.c b/drivers/hv/ring_buffer.c index cd49cb1..f8eee6e 100644 --- a/drivers/hv/ring_buffer.c +++ b/drivers/hv/ring_buffer.c @@ -135,7 +135,8 @@ hv_get_next_readlocation_withoffset(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; } @@ -179,7 +180,8 @@ 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; } @@ -201,7 +203,8 @@ 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; } -- 2.7.4 _______________________________________________ devel mailing list devel@xxxxxxxxxxxxxxxxxxxxxx http://driverdev.linuxdriverproject.org/mailman/listinfo/driverdev-devel
