[4/6] vxge: prefetch RxD descriptors
From: Benjamin LaHaise <hidden>
Date: 2009-08-04 20:39:58
Subsystem:
networking drivers, the rest · Maintainers:
Andrew Lunn, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds
This patch prefetches RxD descriptors which helps to lower the latency of a cache miss in vxge_hw_ring_rxd_next_completed. This lowers the % of CPU time used by vxge_hw_ring_rxd_next_completed() where the descriptor is accessed in profiling netperf on a P4 Xeon from 1.5% to 1.0%. Signed-off-by: Benjamin LaHaise <redacted> Signed-off-by: Sreenivasa Honnur <redacted> Signed-off-by: Ramkrishna Vepa <redacted> ---
--- a/drivers/net/vxge/vxge-main.c.orig 2009-05-04 15:04:14.000000000 -0700
+++ b/drivers/net/vxge/vxge-main.c 2009-05-04 14:58:48.000000000 -0700@@ -445,6 +431,7 @@ vxge_rx_1b_compl(struct __vxge_hw_ring * vxge_hw_ring_replenish(ringh, 0); do { + prefetch((char *)dtr + L1_CACHE_BYTES); rx_priv = vxge_hw_ring_rxd_private_get(dtr); skb = rx_priv->skb; data_size = rx_priv->data_size;
diff --git a/drivers/net/vxge/vxge-traffic.c b/drivers/net/vxge/vxge-traffic.c
index 7be0ae1..9a6b10d 100644
--- a/drivers/net/vxge/vxge-traffic.c
+++ b/drivers/net/vxge/vxge-traffic.c@@ -731,6 +731,7 @@ vxge_hw_channel_dtr_try_complete(struct __vxge_hw_channel *channel, void **dtrh) vxge_assert(channel->compl_index < channel->length); *dtrh = channel->work_arr[channel->compl_index]; + prefetch(*dtrh); } /*