From 15e1674de747d58c5a6154ba6e85bc61e5009b08 Mon Sep 17 00:00:00 2001 From: Stephen Hemminger Date: Sun, 25 Jun 2017 12:30:29 -0700 Subject: [PATCH] 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 Signed-off-by: K. Y. Srinivasan Signed-off-by: Greg Kroah-Hartman --- drivers/hv/ring_buffer.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/drivers/hv/ring_buffer.c b/drivers/hv/ring_buffer.c index 741daa6e2fc7..12eb8caa4263 100644 --- a/drivers/hv/ring_buffer.c +++ b/drivers/hv/ring_buffer.c @@ -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); -- GitLab