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Eric Dumazet says: ==================== tcp: TCP TS option use 1 ms clock 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 ==================== Signed-off-by: David S. Miller <davem@davemloft.net>
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. Please read the Documentation/process/changes.rst file, as it contains the requirements for building and running the kernel, and information about the problems which may result by upgrading your kernel.