mirror of https://github.com/hak5/openwrt-owl.git
68 lines
2.2 KiB
Diff
68 lines
2.2 KiB
Diff
[RFC] rt2x00: For drivers that only need L2 padding don't realign frames
|
|
|
|
Signed-off-by: Helmut Schaa <helmut.schaa@...>
|
|
---
|
|
|
|
Ivo, Gertjan, do you remeber by any chance why this alignment stuff was added
|
|
in the first place? Was it because of DMA restrictions?
|
|
|
|
While doing some profiling on the rt3052 SoC I noticed that 30-40% time was
|
|
spent in memmove calls. And the culprit is the memmove aligning the payload
|
|
to a 4byte boundary since that has to move a whole bunch of data.
|
|
|
|
Interesstingly the legacy drivers insert an l2pad between the header and the
|
|
payload but doesn't realign the payload itself to a 4-byte boundary. Hence,
|
|
I came up with this patch and indeed CPU usage improves impressively.
|
|
|
|
Only tested on rt2800pci!
|
|
|
|
Thanks,
|
|
Helmut
|
|
|
|
drivers/net/wireless/rt2x00/rt2x00queue.c | 30 +++-------------------------
|
|
1 files changed, 4 insertions(+), 26 deletions(-)
|
|
|
|
--- a/drivers/net/wireless/rt2x00/rt2x00queue.c
|
|
+++ b/drivers/net/wireless/rt2x00/rt2x00queue.c
|
|
@@ -163,36 +163,14 @@ void rt2x00queue_align_frame(struct sk_b
|
|
void rt2x00queue_insert_l2pad(struct sk_buff *skb, unsigned int header_length)
|
|
{
|
|
unsigned int payload_length = skb->len - header_length;
|
|
- unsigned int header_align = ALIGN_SIZE(skb, 0);
|
|
- unsigned int payload_align = ALIGN_SIZE(skb, header_length);
|
|
unsigned int l2pad = payload_length ? L2PAD_SIZE(header_length) : 0;
|
|
|
|
- /*
|
|
- * Adjust the header alignment if the payload needs to be moved more
|
|
- * than the header.
|
|
- */
|
|
- if (payload_align > header_align)
|
|
- header_align += 4;
|
|
-
|
|
- /* There is nothing to do if no alignment is needed */
|
|
- if (!header_align)
|
|
+ if (!l2pad)
|
|
return;
|
|
|
|
- /* Reserve the amount of space needed in front of the frame */
|
|
- skb_push(skb, header_align);
|
|
-
|
|
- /*
|
|
- * Move the header.
|
|
- */
|
|
- memmove(skb->data, skb->data + header_align, header_length);
|
|
-
|
|
- /* Move the payload, if present and if required */
|
|
- if (payload_length && payload_align)
|
|
- memmove(skb->data + header_length + l2pad,
|
|
- skb->data + header_length + l2pad + payload_align,
|
|
- payload_length);
|
|
-
|
|
- /* Trim the skb to the correct size */
|
|
+ /* insert l2pad -> Move header */
|
|
+ skb_push(skb, l2pad);
|
|
+ memmove(skb->data, skb->data + l2pad, header_length);
|
|
skb_trim(skb, header_length + l2pad + payload_length);
|
|
}
|
|
|