Hi,
On 01/18/2018 12:42 AM, Miroslav Lichvar wrote: > On Wed, Jan 17, 2018 at 03:06:12PM -0800, Jesus Sanchez-Palencia wrote: >> From: Richard Cochran <rcoch...@linutronix.de> >> >> This patch introduces SO_TXTIME. User space enables this option in >> order to pass a desired future transmit time in a CMSG when calling >> sendmsg(2). >> >> A new field is added to struct sockcm_cookie, and the tstamp from >> skbuffs will be used later on. > > In the discussion about the v1 patchset, there was a question if the > cmsg should include a clockid_t. Without that, how can an application > prevent the packet from being sent using an incorrect clock, e.g. > the system clock when it expects it to be a PHC, or a different PHC > when the socket is not bound to a specific interface? > > At least in some applications it would be preferred to not sent a > packet at all instead of sending it at a wrong time. > > Please keep in mind that the PHCs and the system clock don't have to > be synchronized to each other. If I understand the rest of the series > correctly, there is an assumption that the PHCs are keeping time in > TAI and CLOCK_TAI can be used as a fallback. Just to double-check, imagine that I've configured the qdisc for SW best-effort and with clockid CLOCK_REALTIME. When it receives a packet with the clockid of a /dev/ptpX, the qdisc should just drop that packet, right? Or would this block any use-cases that I couldn't think of ? Thanks, Jesus
