From 757647e10e55c01fb7a9c4356529442e316a7c72 Mon Sep 17 00:00:00 2001 From: Vitaly Kuznetsov Date: Mon, 25 Jan 2016 16:00:41 +0100 Subject: [PATCH] hv_netvsc: use skb_get_hash() instead of a homegrown implementation Recent changes to 'struct flow_keys' (e.g commit d34af823ff40 ("net: Add VLAN ID to flow_keys")) introduced a performance regression in netvsc driver. Is problem is, however, not the above mentioned commit but the fact that netvsc_set_hash() function did some assumptions on the struct flow_keys data layout and this is wrong. Get rid of netvsc_set_hash() by switching to skb_get_hash(). This change will also imply switching to Jenkins hash from the currently used Toeplitz but it seems there is no good excuse for Toeplitz to stay. Signed-off-by: Vitaly Kuznetsov Acked-by: Eric Dumazet Signed-off-by: David S. Miller --- drivers/net/hyperv/netvsc_drv.c | 67 ++------------------------------- 1 file changed, 3 insertions(+), 64 deletions(-) diff --git a/drivers/net/hyperv/netvsc_drv.c b/drivers/net/hyperv/netvsc_drv.c index 1c8db9afdcda..1d3a66563bac 100644 --- a/drivers/net/hyperv/netvsc_drv.c +++ b/drivers/net/hyperv/netvsc_drv.c @@ -196,65 +196,6 @@ static void *init_ppi_data(struct rndis_message *msg, u32 ppi_size, return ppi; } -union sub_key { - u64 k; - struct { - u8 pad[3]; - u8 kb; - u32 ka; - }; -}; - -/* Toeplitz hash function - * data: network byte order - * return: host byte order - */ -static u32 comp_hash(u8 *key, int klen, void *data, int dlen) -{ - union sub_key subk; - int k_next = 4; - u8 dt; - int i, j; - u32 ret = 0; - - subk.k = 0; - subk.ka = ntohl(*(u32 *)key); - - for (i = 0; i < dlen; i++) { - subk.kb = key[k_next]; - k_next = (k_next + 1) % klen; - dt = ((u8 *)data)[i]; - for (j = 0; j < 8; j++) { - if (dt & 0x80) - ret ^= subk.ka; - dt <<= 1; - subk.k <<= 1; - } - } - - return ret; -} - -static bool netvsc_set_hash(u32 *hash, struct sk_buff *skb) -{ - struct flow_keys flow; - int data_len; - - if (!skb_flow_dissect_flow_keys(skb, &flow, 0) || - !(flow.basic.n_proto == htons(ETH_P_IP) || - flow.basic.n_proto == htons(ETH_P_IPV6))) - return false; - - if (flow.basic.ip_proto == IPPROTO_TCP) - data_len = 12; - else - data_len = 8; - - *hash = comp_hash(netvsc_hash_key, HASH_KEYLEN, &flow, data_len); - - return true; -} - static u16 netvsc_select_queue(struct net_device *ndev, struct sk_buff *skb, void *accel_priv, select_queue_fallback_t fallback) { @@ -267,11 +208,9 @@ static u16 netvsc_select_queue(struct net_device *ndev, struct sk_buff *skb, if (nvsc_dev == NULL || ndev->real_num_tx_queues <= 1) return 0; - if (netvsc_set_hash(&hash, skb)) { - q_idx = nvsc_dev->send_table[hash % VRSS_SEND_TAB_SIZE] % - ndev->real_num_tx_queues; - skb_set_hash(skb, hash, PKT_HASH_TYPE_L3); - } + hash = skb_get_hash(skb); + q_idx = nvsc_dev->send_table[hash % VRSS_SEND_TAB_SIZE] % + ndev->real_num_tx_queues; if (!nvsc_dev->chn_table[q_idx]) q_idx = 0; -- 2.20.1