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vmbus: add prefetch to ring buffer iterator 

When iterating over incoming ring elements from the host, prefetch
the next descriptor so that it is cache hot.

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 2017-06-25 12:30:29 -07:00 committed by Greg Kroah-Hartman
parent 03bad714a1
commit 15e1674de7
1 changed files with 6 additions and 1 deletions
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7
drivers/hv/ring_buffer.c
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@ -357,11 +357,16 @@ static u32 hv_pkt_iter_avail(const struct hv_ring_buffer_info *rbi)
struct vmpacket_descriptor *hv_pkt_iter_first(struct vmbus_channel *channel)
{
struct hv_ring_buffer_info *rbi = &channel->inbound;
struct vmpacket_descriptor *desc;
if (hv_pkt_iter_avail(rbi) < sizeof(struct vmpacket_descriptor))
return NULL;
return hv_get_ring_buffer(rbi) + rbi->priv_read_index;
desc = hv_get_ring_buffer(rbi) + rbi->priv_read_index;
if (desc)
prefetch((char *)desc + (desc->len8 << 3));
return desc;
}
EXPORT_SYMBOL_GPL(hv_pkt_iter_first);