Re: [PATCH net-next 7/8] sock: enable timestamping using control messages
From: Willem de Bruijn <willemdebruijn.kernel@gmail.com>
Date: 2016-03-31 03:39:50
On Wed, Mar 30, 2016 at 6:37 PM, Soheil Hassas Yeganeh [off-list ref] wrote:
From: Soheil Hassas Yeganeh <redacted> Currently, SOL_TIMESTAMPING can only be enabled using setsockopt. This is very costly when users want to sample writes to gather tx timestamps. Add support for enabling SO_TIMESTAMPING via control messages by using tsflags added in `struct sockcm_cookie` (added in the previous patches in this series) to set the tx_flags of the last skb created in a sendmsg. With this patch, the timestamp recording bits in tx_flags of the skbuff is overridden if SO_TIMESTAMPING is passed in a cmsg. Please note that this is only effective for overriding the recording timestamps flags. Users should enable timestamp reporting (e.g., SOF_TIMESTAMPING_SOFTWARE | SOF_TIMESTAMPING_OPT_ID) using socket options and then should ask for SOF_TIMESTAMPING_TX_* using control messages per sendmsg to sample timestamps for each write. Signed-off-by: Soheil Hassas Yeganeh <redacted>
Acked-by: Willem de Bruijn <willemb@google.com>