From 60b86665af0dfbeebda8aae43f0ba451cd2dcfe5 Mon Sep 17 00:00:00 2001 From: stephen hemminger Date: Thu, 8 Jun 2017 16:21:18 -0700 Subject: [PATCH] netvsc: optimize calculation of number of slots Speed up transmit check for fragmented packets by using existing macros to compute number of pages, and eliminate loop since skb fragments each take a page. Number of slots is also unsigned. Signed-off-by: Stephen Hemminger Signed-off-by: David S. Miller --- drivers/net/hyperv/netvsc_drv.c | 43 ++++++++------------------------- 1 file changed, 10 insertions(+), 33 deletions(-) diff --git a/drivers/net/hyperv/netvsc_drv.c b/drivers/net/hyperv/netvsc_drv.c index 2564ac83eb64..df6d8e28949e 100644 --- a/drivers/net/hyperv/netvsc_drv.c +++ b/drivers/net/hyperv/netvsc_drv.c @@ -345,34 +345,14 @@ static u32 init_page_array(void *hdr, u32 len, struct sk_buff *skb, return slots_used; } -static int count_skb_frag_slots(struct sk_buff *skb) -{ - int i, frags = skb_shinfo(skb)->nr_frags; - int pages = 0; - - for (i = 0; i < frags; i++) { - skb_frag_t *frag = skb_shinfo(skb)->frags + i; - unsigned long size = skb_frag_size(frag); - unsigned long offset = frag->page_offset; - - /* Skip unused frames from start of page */ - offset &= ~PAGE_MASK; - pages += PFN_UP(offset + size); - } - return pages; -} - -static int netvsc_get_slots(struct sk_buff *skb) +/* Estimate number of page buffers neede to transmit + * Need at most 2 for RNDIS header plus skb body and fragments. + */ +static unsigned int netvsc_get_slots(const struct sk_buff *skb) { - char *data = skb->data; - unsigned int offset = offset_in_page(data); - unsigned int len = skb_headlen(skb); - int slots; - int frag_slots; - - slots = DIV_ROUND_UP(offset + len, PAGE_SIZE); - frag_slots = count_skb_frag_slots(skb); - return slots + frag_slots; + return PFN_UP(offset_in_page(skb->data) + skb_headlen(skb)) + + skb_shinfo(skb)->nr_frags + + 2; } static u32 net_checksum_info(struct sk_buff *skb) @@ -410,21 +390,18 @@ static int netvsc_start_xmit(struct sk_buff *skb, struct net_device *net) struct hv_page_buffer page_buf[MAX_PAGE_BUFFER_COUNT]; struct hv_page_buffer *pb = page_buf; - /* We will atmost need two pages to describe the rndis - * header. We can only transmit MAX_PAGE_BUFFER_COUNT number + /* We can only transmit MAX_PAGE_BUFFER_COUNT number * of pages in a single packet. If skb is scattered around * more pages we try linearizing it. */ - - num_data_pgs = netvsc_get_slots(skb) + 2; - + num_data_pgs = netvsc_get_slots(skb); if (unlikely(num_data_pgs > MAX_PAGE_BUFFER_COUNT)) { ++net_device_ctx->eth_stats.tx_scattered; if (skb_linearize(skb)) goto no_memory; - num_data_pgs = netvsc_get_slots(skb) + 2; + num_data_pgs = netvsc_get_slots(skb); if (num_data_pgs > MAX_PAGE_BUFFER_COUNT) { ++net_device_ctx->eth_stats.tx_too_big; goto drop; -- 2.45.2