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cfg80211: reuse existing page fragments in A-MSDU rx

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This massively reduces data copying and thus improves rx performance

Signed-off-by: Felix Fietkau <nbd@openwrt.org>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
This commit is contained in:
Felix Fietkau 2016-02-08 14:34:42 +01:00 committed by Johannes Berg
parent 2bf0ccc709
commit 2b67f944f8
1 changed files with 77 additions and 5 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

84
net/wireless/util.c
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@ -644,23 +644,93 @@ int ieee80211_data_from_8023(struct sk_buff *skb, const u8 *addr,
}
EXPORT_SYMBOL(ieee80211_data_from_8023);
static struct sk_buff *
__ieee80211_amsdu_copy(struct sk_buff *skb, unsigned int hlen,
static void
__frame_add_frag(struct sk_buff *skb, struct page *page,
void *ptr, int len, int size)
{
struct skb_shared_info *sh = skb_shinfo(skb);
int page_offset;
atomic_inc(&page->_count);
page_offset = ptr - page_address(page);
skb_add_rx_frag(skb, sh->nr_frags, page, page_offset, len, size);
}
static void
__ieee80211_amsdu_copy_frag(struct sk_buff *skb, struct sk_buff *frame,
int offset, int len)
{
struct skb_shared_info *sh = skb_shinfo(skb);
const skb_frag_t *frag = &sh->frags[-1];
struct page *frag_page;
void *frag_ptr;
int frag_len, frag_size;
int head_size = skb->len - skb->data_len;
int cur_len;
frag_page = virt_to_head_page(skb->head);
frag_ptr = skb->data;
frag_size = head_size;
while (offset >= frag_size) {
offset -= frag_size;
frag++;
frag_page = skb_frag_page(frag);
frag_ptr = skb_frag_address(frag);
frag_size = skb_frag_size(frag);
}
frag_ptr += offset;
frag_len = frag_size - offset;
cur_len = min(len, frag_len);
__frame_add_frag(frame, frag_page, frag_ptr, cur_len, frag_size);
len -= cur_len;
while (len > 0) {
frag++;
frag_len = skb_frag_size(frag);
cur_len = min(len, frag_len);
__frame_add_frag(frame, skb_frag_page(frag),
skb_frag_address(frag), cur_len, frag_len);
len -= cur_len;
}
}
static struct sk_buff *
__ieee80211_amsdu_copy(struct sk_buff *skb, unsigned int hlen,
int offset, int len, bool reuse_frag)
{
struct sk_buff *frame;
int cur_len = len;
if (skb->len - offset < len)
return NULL;
/*
* When reusing framents, copy some data to the head to simplify
* ethernet header handling and speed up protocol header processing
* in the stack later.
*/
if (reuse_frag)
cur_len = min_t(int, len, 32);
/*
* Allocate and reserve two bytes more for payload
* alignment since sizeof(struct ethhdr) is 14.
*/
frame = dev_alloc_skb(hlen + sizeof(struct ethhdr) + 2 + len);
frame = dev_alloc_skb(hlen + sizeof(struct ethhdr) + 2 + cur_len);
skb_reserve(frame, hlen + sizeof(struct ethhdr) + 2);
skb_copy_bits(skb, offset, skb_put(frame, len), len);
skb_copy_bits(skb, offset, skb_put(frame, cur_len), cur_len);
len -= cur_len;
if (!len)
return frame;
offset += cur_len;
__ieee80211_amsdu_copy_frag(skb, frame, offset, len);
return frame;
}
@ -676,6 +746,7 @@ void ieee80211_amsdu_to_8023s(struct sk_buff *skb, struct sk_buff_head *list,
u8 *payload;
int offset = 0, remaining, err;
struct ethhdr eth;
bool reuse_frag = skb->head_frag && !skb_has_frag_list(skb);
bool reuse_skb = false;
bool last = false;
@ -703,12 +774,13 @@ void ieee80211_amsdu_to_8023s(struct sk_buff *skb, struct sk_buff_head *list,
offset += sizeof(struct ethhdr);
/* reuse skb for the last subframe */
last = remaining <= subframe_len + padding;
if (!skb_is_nonlinear(skb) && last) {
if (!skb_is_nonlinear(skb) && !reuse_frag && last) {
skb_pull(skb, offset);
frame = skb;
reuse_skb = true;
} else {
frame = __ieee80211_amsdu_copy(skb, hlen, offset, len);
frame = __ieee80211_amsdu_copy(skb, hlen, offset, len,
reuse_frag);
if (!frame)
goto purge;