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* Make use of the stats(3) framework in the TCP stack.Edward Tomasz Napierala2019-12-021-2/+2
| | | | | | | | | | | | | | | | | | | | | | | | | This makes it possible to retrieve per-connection statistical information such as the receive window size, RTT, or goodput, using a newly added TCP_STATS getsockopt(3) option, and extract them using the stats_voistat_fetch(3) API. See the net/tcprtt port for an example consumer of this API. Compared to the existing TCP_INFO system, the main differences are that this mechanism is easy to extend without breaking ABI, and provides statistical information instead of raw "snapshots" of values at a given point in time. stats(3) is more generic and can be used in both userland and the kernel. Reviewed by: thj Tested by: thj Obtained from: Netflix Relnotes: yes Sponsored by: Klara Inc, Netflix Differential Revision: https://reviews.freebsd.org/D20655 Notes: svn path=/head/; revision=355304
* Introduce stats(3), a flexible statistics gathering API.Edward Tomasz Napierala2019-10-071-0/+14
This provides a framework to define a template describing a set of "variables of interest" and the intended way for the framework to maintain them (for example the maximum, sum, t-digest, or a combination thereof). Afterwards the user code feeds in the raw data, and the framework maintains these variables inside a user-provided, opaque stats blobs. The framework also provides a way to selectively extract the stats from the blobs. The stats(3) framework can be used in both userspace and the kernel. See the stats(3) manual page for details. This will be used by the upcoming TCP statistics gathering code, https://reviews.freebsd.org/D20655. The stats(3) framework is disabled by default for now, except in the NOTES kernel (for QA); it is expected to be enabled in amd64 GENERIC after a cool down period. Reviewed by: sef (earlier version) Obtained from: Netflix Relnotes: yes Sponsored by: Klara Inc, Netflix Differential Revision: https://reviews.freebsd.org/D20477 Notes: svn path=/head/; revision=353283