[romed]

This post groks QUIC. The most important thing about QUIC is it frees applications from the tyranny of the kernel TCP state machine. Today all TCP sockets (at least, on Linux) are subject to the same system-wide parameters of the TCP state machine, none of which are appropriate for any particular application. With QUIC we will finally have each application in control of its own retry timers and other parameters. That is going to be quite beneficial, especially on mobile where packet loss is so common.

[blitmap]

setsockopt(fd, SOL_SOCKET, SO_RCVTIMEO, ...)

setsockopt(fd, SOL_SOCKET, SO_SNDTIMEO, ...)

?

I'm not dismissing QUIC, but it is in your control to redefine those defaults. Maybe in 2020 we'll be grappling back toward [sane] defaults.

[romed]

Those do not affect TCP state machine parameters like RTO(min), ATO, and TLP timeout. These are internal to the kernel and are either static, or can only be set systemwide. For example the minimum delayed ack timeout in Linux is just 40ms and can't be changed except by recompiling the kernel. 40ms is a totally inappropriate number for ATO in a datacenter or other low-latency setting. Other numbers like RTO(min) are specified in RFCs as 200ms, again completely inappropriate in a low-latency setting.

QUIC also frees us from other outdated misfeatures of TCP such as timestamps in milliseconds when they should be in microseconds.