From: Eric Dumazet <eduma...@google.com> Date: Tue, 16 May 2017 13:59:59 -0700
> TCP Timestamps option is defined in RFC 7323 > > Traditionally on linux, it has been tied to the internal > 'jiffy' variable, because it had been a cheap and good enough > generator. > > Unfortunately some distros use HZ=250 or even HZ=100 leading > to not very useful TCP timestamps. > > For TCP flows in the DC, Google has used usec resolution for more > than two years with great success [1]. > RCVBUF autotuning is more precise. > > This series converts tp->tcp_mstamp to a plain u64 value storing > a 1 usec TCP clock. > > This choice will allow us to upstream the 1 usec TS option as > discussed in IETF 97. > > Kathleen Nichols [2] and others advocate for 1ms TS clocks for > network analysis. (1ms being the lowest value supported by RFC 7323.) > > [1] > https://www.ietf.org/proceedings/97/slides/slides-97-tcpm-tcp-options-for-low-latency-00.pdf > [2] http://netseminar.stanford.edu/seminars/02_02_17.pdf Series applied, thanks Eric.
