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mptcp: use copy_from_iter helpers on transmit
The perf traces show an high cost for the MPTCP transmit path memcpy. It turn out that the helper currently in use carries quite a bit of unneeded overhead, e.g. to map/unmap the memory pages. Moving to the 'copy_from_iter' variant removes such overhead and additionally gains the no-cache support. Reviewed-by: Mat Martineau <martineau@kernel.org> Signed-off-by: Paolo Abeni <pabeni@redhat.com> Signed-off-by: Mat Martineau <martineau@kernel.org> Link: https://lore.kernel.org/r/20231023-send-net-next-20231023-2-v1-6-9dc60939d371@kernel.org Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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1 changed files with 15 additions and 4 deletions
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@ -1760,6 +1760,18 @@ static int mptcp_sendmsg_fastopen(struct sock *sk, struct msghdr *msg,
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return ret;
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}
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static int do_copy_data_nocache(struct sock *sk, int copy,
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struct iov_iter *from, char *to)
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{
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if (sk->sk_route_caps & NETIF_F_NOCACHE_COPY) {
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if (!copy_from_iter_full_nocache(to, copy, from))
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return -EFAULT;
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} else if (!copy_from_iter_full(to, copy, from)) {
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return -EFAULT;
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}
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return 0;
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}
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static int mptcp_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
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{
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struct mptcp_sock *msk = mptcp_sk(sk);
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@ -1833,11 +1845,10 @@ static int mptcp_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
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if (!sk_wmem_schedule(sk, total_ts))
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goto wait_for_memory;
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if (copy_page_from_iter(dfrag->page, offset, psize,
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&msg->msg_iter) != psize) {
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ret = -EFAULT;
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ret = do_copy_data_nocache(sk, psize, &msg->msg_iter,
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page_address(dfrag->page) + offset);
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if (ret)
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goto do_error;
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}
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/* data successfully copied into the write queue */
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sk_forward_alloc_add(sk, -total_ts);
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