diff mbox

[net-next,1/3] netvsc: optimize calculation of number of slots

Message ID 20170529183159.22205-1-sthemmin@microsoft.com
State Changes Requested, archived
Delegated to: David Miller
Headers show

Commit Message

Stephen Hemminger May 29, 2017, 6:31 p.m. UTC 
Speed up transmit check for fragmented packets by using existing
macros to compute number of pages, and eliminate loop since
each skb fragment is only one page.

Signed-off-by: Stephen Hemminger <sthemmin@microsoft.com>
---
 drivers/net/hyperv/netvsc_drv.c | 43 ++++++++++-------------------------------
 1 file changed, 10 insertions(+), 33 deletions(-)

Comments

David Miller May 30, 2017, 12:42 a.m. UTC | #1 
Stephen, please provide proper header "[PATCH net-next 0/3] " postings
with your patch series, so we know at a high level what this patch
series is doing, how it is doing it, and why it is doing it that
way.

I've been quite liberal with your patch postings in the past, hoping
you would catch on, but now I'm going to simply enforce what I ask
of every other patch series submitter.

Thanks.
Stephen Hemminger May 30, 2017, 5:16 p.m. UTC | #2 
On Mon, 29 May 2017 20:42:04 -0400 (EDT)
David Miller <davem@davemloft.net> wrote:

> Stephen, please provide proper header "[PATCH net-next 0/3] " postings
> with your patch series, so we know at a high level what this patch
> series is doing, how it is doing it, and why it is doing it that
> way.

Sure, these were just misc small cleanups. Prefer to send them out
in small chunks, not mixed with bug fixes and new features.

> I've been quite liberal with your patch postings in the past, hoping
> you would catch on, but now I'm going to simply enforce what I ask
> of every other patch series submitter.

Sorry, thought it was obvious from content.
diff mbox

Patch

diff --git a/drivers/net/hyperv/netvsc_drv.c b/drivers/net/hyperv/netvsc_drv.c
index 4421a6d00375..548c78863ce9 100644
--- a/drivers/net/hyperv/netvsc_drv.c
+++ b/drivers/net/hyperv/netvsc_drv.c
@@ -343,34 +343,14 @@  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)
@@ -408,21 +388,18 @@  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;