lkml.org 
[lkml]   [2021]   [Nov]   [30]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Subject[RFC 04/12] net: add zerocopy_sg_from_iter for bvec
    Date
    Add a separate path for bvec iterators in __zerocopy_sg_from_iter, first
    it's quite faster but also will be needed to optimise out
    get/put_page()

    Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
    ---
    net/core/datagram.c | 54 +++++++++++++++++++++++++++++++++++++++++++++
    1 file changed, 54 insertions(+)

    diff --git a/net/core/datagram.c b/net/core/datagram.c
    index ee290776c661..e00f7e0a7a0a 100644
    --- a/net/core/datagram.c
    +++ b/net/core/datagram.c
    @@ -616,11 +616,65 @@ int skb_copy_datagram_from_iter(struct sk_buff *skb, int offset,
    }
    EXPORT_SYMBOL(skb_copy_datagram_from_iter);

    +static int __zerocopy_sg_from_bvec(struct sock *sk, struct sk_buff *skb,
    + struct iov_iter *from, size_t length)
    +{
    + int ret, frag = skb_shinfo(skb)->nr_frags;
    + struct bvec_iter bi;
    + struct bio_vec v;
    + ssize_t copied = 0;
    + unsigned long truesize = 0;
    +
    + bi.bi_size = min(from->count, length);
    + bi.bi_bvec_done = from->iov_offset;
    + bi.bi_idx = 0;
    +
    + while (bi.bi_size) {
    + if (frag == MAX_SKB_FRAGS) {
    + ret = -EMSGSIZE;
    + goto out;
    + }
    +
    + /*
    + * TODO: ignore compound pages for now, all bvec from io_uring
    + * are within boundaries of a single page.
    + */
    + v = mp_bvec_iter_bvec(from->bvec, bi);
    + copied += v.bv_len;
    + truesize += PAGE_ALIGN(v.bv_len + v.bv_offset);
    + get_page(v.bv_page);
    + skb_fill_page_desc(skb, frag++, v.bv_page, v.bv_offset, v.bv_len);
    + bvec_iter_advance_single(from->bvec, &bi, v.bv_len);
    + }
    + ret = 0;
    +out:
    + skb->data_len += copied;
    + skb->len += copied;
    + skb->truesize += truesize;
    +
    + if (sk && sk->sk_type == SOCK_STREAM) {
    + sk_wmem_queued_add(sk, truesize);
    + if (!skb_zcopy_pure(skb))
    + sk_mem_charge(sk, truesize);
    + } else {
    + refcount_add(truesize, &skb->sk->sk_wmem_alloc);
    + }
    +
    + from->bvec += bi.bi_idx;
    + from->nr_segs -= bi.bi_idx;
    + from->count = bi.bi_size;
    + from->iov_offset = bi.bi_bvec_done;
    + return ret;
    +}
    +
    int __zerocopy_sg_from_iter(struct sock *sk, struct sk_buff *skb,
    struct iov_iter *from, size_t length)
    {
    int frag = skb_shinfo(skb)->nr_frags;

    + if (iov_iter_is_bvec(from))
    + return __zerocopy_sg_from_bvec(sk, skb, from, length);
    +
    while (length && iov_iter_count(from)) {
    struct page *pages[MAX_SKB_FRAGS];
    struct page *last_head = NULL;
    --
    2.34.0
    \
     
     \ /
      Last update: 2021-11-30 16:25    [W:4.088 / U:0.772 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site