[v2,15/16] vhost: check whether disable software pre-fetch
diff mbox series

Message ID 20190919163643.24130-16-yong.liu@intel.com
State Superseded, archived
Headers show
Series
  • vhost packed ring performance optimization
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Checks

Context Check Description
ci/checkpatch success coding style OK
ci/Intel-compilation fail Compilation issues

Commit Message

Liu, Yong Sept. 19, 2019, 4:36 p.m. UTC
Disable software pre-fetch actions on Skylake and Cascadelake platforms.
Hardware can fetch needed data for vhost, additional software pre-fetch
will have impact on performance.

Signed-off-by: Marvin Liu <yong.liu@intel.com>

Patch
diff mbox series

diff --git a/lib/librte_vhost/Makefile b/lib/librte_vhost/Makefile
index 30839a001..5f3b42e56 100644
--- a/lib/librte_vhost/Makefile
+++ b/lib/librte_vhost/Makefile
@@ -16,6 +16,12 @@  CFLAGS += -I vhost_user
 CFLAGS += -fno-strict-aliasing
 LDLIBS += -lpthread
 
+AVX512_SUPPORT=$(shell $(CC) -march=native -dM -E - </dev/null |grep AVX512F)
+
+ifneq ($(AVX512_SUPPORT),)
+CFLAGS += -DDISABLE_SWPREFETCH
+endif
+
 ifeq ($(RTE_TOOLCHAIN), gcc)
 ifeq ($(shell test $(GCC_VERSION) -ge 83 && echo 1), 1)
 CFLAGS += -DSUPPORT_GCC_UNROLL_PRAGMA
diff --git a/lib/librte_vhost/virtio_net.c b/lib/librte_vhost/virtio_net.c
index 066514e43..357517cdd 100644
--- a/lib/librte_vhost/virtio_net.c
+++ b/lib/librte_vhost/virtio_net.c
@@ -478,7 +478,9 @@  map_one_desc(struct virtio_net *dev, struct vhost_virtqueue *vq,
 		if (unlikely(!desc_addr))
 			return -1;
 
+#ifndef DISABLE_SWPREFETCH
 		rte_prefetch0((void *)(uintptr_t)desc_addr);
+#endif
 
 		buf_vec[vec_id].buf_iova = desc_iova;
 		buf_vec[vec_id].buf_addr = desc_addr;
@@ -999,7 +1001,9 @@  virtio_dev_rx_split(struct virtio_net *dev, struct vhost_virtqueue *vq,
 	 */
 	rte_smp_rmb();
 
+#ifndef DISABLE_SWPREFETCH
 	rte_prefetch0(&vq->avail->ring[vq->last_avail_idx & (vq->size - 1)]);
+#endif
 
 	for (pkt_idx = 0; pkt_idx < count; pkt_idx++) {
 		uint32_t pkt_len = pkts[pkt_idx]->pkt_len + dev->vhost_hlen;
@@ -1093,7 +1097,9 @@  virtio_dev_rx_burst_packed(struct virtio_net *dev, struct vhost_virtqueue *vq,
 
 	UNROLL_PRAGMA(PRAGMA_PARAM)
 	for (i = 0; i < PACKED_DESCS_BURST; i++) {
+#ifndef DISABLE_SWPREFETCH
 		rte_prefetch0((void *)(uintptr_t)desc_addrs[i]);
+#endif
 		hdrs[i] = (struct virtio_net_hdr_mrg_rxbuf *)desc_addrs[i];
 		lens[i] = pkts[i]->pkt_len + dev->vhost_hlen;
 	}
@@ -1647,7 +1653,9 @@  virtio_dev_tx_split(struct virtio_net *dev, struct vhost_virtqueue *vq,
 	 */
 	rte_smp_rmb();
 
+#ifndef DISABLE_SWPREFETCH
 	rte_prefetch0(&vq->avail->ring[vq->last_avail_idx & (vq->size - 1)]);
+#endif
 
 	VHOST_LOG_DEBUG(VHOST_DATA, "(%d) %s\n", dev->vid, __func__);
 
@@ -1818,7 +1826,9 @@  virtio_dev_tx_burst_packed(struct virtio_net *dev, struct vhost_virtqueue *vq,
 
 	UNROLL_PRAGMA(PRAGMA_PARAM)
 	for (i = 0; i < PACKED_DESCS_BURST; i++) {
+#ifndef DISABLE_SWPREFETCH
 		rte_prefetch0((void *)(uintptr_t)desc_addrs[i]);
+#endif
 		rte_memcpy(rte_pktmbuf_mtod_offset(pkts[i], void *, 0),
 			   (void *)(uintptr_t)(desc_addrs[i] + buf_offset),
 			   pkts[i]->pkt_len);