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mptcp: use copy_from_iter helpers on transmit

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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>
This commit is contained in:
Paolo Abeni 2023-10-23 13:44:39 -07:00 committed by Jakub Kicinski
parent 5684ab1a0e
commit 0ffe8e7490
1 changed files with 15 additions and 4 deletions
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19
net/mptcp/protocol.c
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@ -1760,6 +1760,18 @@ static int mptcp_sendmsg_fastopen(struct sock *sk, struct msghdr *msg,
return ret;
}
static int do_copy_data_nocache(struct sock *sk, int copy,
struct iov_iter *from, char *to)
{
if (sk->sk_route_caps & NETIF_F_NOCACHE_COPY) {
if (!copy_from_iter_full_nocache(to, copy, from))
return -EFAULT;
} else if (!copy_from_iter_full(to, copy, from)) {
return -EFAULT;
}
return 0;
}
static int mptcp_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
{
struct mptcp_sock *msk = mptcp_sk(sk);
@ -1833,11 +1845,10 @@ static int mptcp_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
if (!sk_wmem_schedule(sk, total_ts))
goto wait_for_memory;
if (copy_page_from_iter(dfrag->page, offset, psize,
&msg->msg_iter) != psize) {
ret = -EFAULT;
ret = do_copy_data_nocache(sk, psize, &msg->msg_iter,
page_address(dfrag->page) + offset);
if (ret)
goto do_error;
}
/* data successfully copied into the write queue */
sk_forward_alloc_add(sk, -total_ts);