Merge pull request #1 from seansp/hv_netsvc_use_reciprocal_divide_to_…

…speed_up_computing_padding

Hv netsvc use reciprocal divide to speed up computing padding

hv-rhel7.x/hv/hyperv_net.h

@@ -149,7 +149,6 @@ struct hv_netvsc_packet {
 
 struct netvsc_device_info {
 	unsigned char mac_adr[ETH_ALEN];
-	int  ring_size;
 	u32 num_chn;
 	u32  send_sections;
 	u32  recv_sections;
@@ -190,6 +189,9 @@ struct rndis_message;
 struct netvsc_device;
 struct net_device_context;
 
+extern u32 netvsc_ring_bytes;
+extern struct reciprocal_value netvsc_ring_reciprocal;
+
 struct netvsc_device *netvsc_device_add(struct hv_device *device,
 					const struct netvsc_device_info *info);
 int netvsc_alloc_recv_comp_ring(struct netvsc_device *net_device, u32 q_idx);
@@ -810,8 +812,6 @@ struct netvsc_device {
 
 	struct rndis_device *extension;
 
-	int ring_size;
-
 	u32 max_pkt; /* max number of pkt in one send, e.g. 8 */
 	u32 pkt_align; /* alignment bytes, e.g. 8 */
 

hv-rhel7.x/hv/netvsc.c

@@ -31,6 +31,7 @@
 #include <asm/sync_bitops.h>
 #include <linux/rtnetlink.h>
 #include <linux/prefetch.h>
+#include <linux/reciprocal_div.h>
 
 #include "hyperv_net.h"
 
@@ -593,14 +594,10 @@ void netvsc_device_remove(struct hv_device *device)
  * Get the percentage of available bytes to write in the ring.
  * The return value is in range from 0 to 100.
  */
-static inline u32 hv_ringbuf_avail_percent(
-		struct hv_ring_buffer_info *ring_info)
+static u32 hv_ringbuf_avail_percent(const struct hv_ring_buffer_info *ring_info)
 {
-	u32 avail_read, avail_write;
-
-	hv_get_ringbuffer_availbytes(ring_info, &avail_read, &avail_write);
-
-	return avail_write * 100 / ring_info->ring_datasize;
+    u32 avail_write = hv_get_bytes_to_write(ring_info);
+    return reciprocal_divide(avail_write * 100, netvsc_ring_reciprocal);
 }
 
 static inline void netvsc_free_send_slot(struct netvsc_device *net_device,
@@ -1252,7 +1249,6 @@ struct netvsc_device *netvsc_device_add(struct hv_device *device,
 				const struct netvsc_device_info *device_info)
 {
 	int i, ret = 0;
-	int ring_size = device_info->ring_size;
 	struct netvsc_device *net_device;
 	struct net_device *ndev = hv_get_drvdata(device);
 	struct net_device_context *net_device_ctx = netdev_priv(ndev);
@@ -1264,8 +1260,6 @@ struct netvsc_device *netvsc_device_add(struct hv_device *device,
 	for (i = 0; i < VRSS_SEND_TAB_SIZE; i++)
 		net_device_ctx->tx_table[i] = 0;
 
-	net_device->ring_size = ring_size;
-
 	/* Because the device uses NAPI, all the interrupt batching and
 	 * control is done via Net softirq, not the channel handling
 	 */
@@ -1292,10 +1286,9 @@ struct netvsc_device *netvsc_device_add(struct hv_device *device,
 		       netvsc_poll, NAPI_POLL_WEIGHT);
 
 	/* Open the channel */
-	ret = vmbus_open(device->channel, ring_size * PAGE_SIZE,
-			 ring_size * PAGE_SIZE, NULL, 0,
-			 netvsc_channel_cb,
-			 net_device->chan_table);
+	ret = vmbus_open(device->channel, netvsc_ring_bytes,
+		netvsc_ring_bytes, NULL, 0,
+		netvsc_channel_cb, net_device->chan_table);
 
 	if (ret != 0) {
 		netif_napi_del(&net_device->chan_table[0].napi);

hv-rhel7.x/hv/netvsc_drv.c

@@ -35,6 +35,7 @@
 #include <linux/slab.h>
 #include <linux/rtnetlink.h>
 #include <linux/netpoll.h>
+#include <linux/reciprocal_div.h>
 
 #include <net/arp.h>
 #include <net/route.h>
@@ -51,9 +52,11 @@
 #define LINKCHANGE_INT (2 * HZ)
 #define VF_TAKEOVER_INT (HZ / 10)
 
-static int ring_size = 128;
-module_param(ring_size, int, S_IRUGO);
+static unsigned int ring_size = 128;
+module_param(ring_size, uint, S_IRUGO);
 MODULE_PARM_DESC(ring_size, "Ring buffer size (# of pages)");
+unsigned int netvsc_ring_bytes;
+struct reciprocal_value netvsc_ring_reciprocal;
 
 static const u32 default_msg = NETIF_MSG_DRV | NETIF_MSG_PROBE |
 		NETIF_MSG_LINK | NETIF_MSG_IFUP |
@@ -906,7 +909,6 @@ static int netvsc_set_channels(struct net_device *net,
 
 	memset(&device_info, 0, sizeof(device_info));
 	device_info.num_chn = count;
-	device_info.ring_size = ring_size;
 	device_info.send_sections = nvdev->send_section_cnt;
 	device_info.send_section_size = nvdev->send_section_size;
 	device_info.recv_sections = nvdev->recv_section_cnt;
@@ -1023,7 +1025,6 @@ static int netvsc_change_mtu(struct net_device *ndev, int mtu)
 		rndis_filter_close(nvdev);
 
 	memset(&device_info, 0, sizeof(device_info));
-	device_info.ring_size = ring_size;
 	device_info.num_chn = nvdev->num_chn;
 	device_info.send_sections = nvdev->send_section_cnt;
 	device_info.send_section_size = nvdev->send_section_size;
@@ -1504,7 +1505,6 @@ static int netvsc_set_ringparam(struct net_device *ndev,
 
 	memset(&device_info, 0, sizeof(device_info));
 	device_info.num_chn = nvdev->num_chn;
-	device_info.ring_size = ring_size;
 	device_info.send_sections = new_tx;
 	device_info.send_section_size = nvdev->send_section_size;
 	device_info.recv_sections = new_rx;
@@ -1962,7 +1962,6 @@ static int netvsc_probe(struct hv_device *dev,
 
 	/* Notify the netvsc driver of the new device */
 	memset(&device_info, 0, sizeof(device_info));
-	device_info.ring_size = ring_size;
 	device_info.num_chn = VRSS_CHANNEL_DEFAULT;
 	device_info.send_sections = NETVSC_DEFAULT_TX;
 	device_info.send_section_size = NETVSC_SEND_SECTION_SIZE;
@@ -2122,11 +2121,13 @@ static int __init netvsc_drv_init(void)
 
 	if (ring_size < RING_SIZE_MIN) {
 		ring_size = RING_SIZE_MIN;
-		pr_info("Increased ring_size to %d (min allowed)\n",
+		pr_info("Increased ring_size to %u (min allowed)\n",
 			ring_size);
 	}
-	ret = vmbus_driver_register(&netvsc_drv);
+	netvsc_ring_bytes = ring_size * PAGE_SIZE;
+	netvsc_ring_reciprocal = reciprocal_value(netvsc_ring_bytes);
 
+	ret = vmbus_driver_register(&netvsc_drv);
 	if (ret)
 		return ret;
 

hv-rhel7.x/hv/rndis_filter.c

@@ -1041,8 +1041,8 @@ static void netvsc_sc_open(struct vmbus_channel *new_sc)
 	/* Set the channel before opening.*/
 	nvchan->channel = new_sc;
 
-	ret = vmbus_open(new_sc, nvscdev->ring_size * PAGE_SIZE,
-			 nvscdev->ring_size * PAGE_SIZE, NULL, 0,
+	ret = vmbus_open(new_sc, netvsc_ring_bytes,
+			 netvsc_ring_bytes, NULL, 0,
 			 netvsc_channel_cb, nvchan);
 
 	if (ret == 0)