uvm: retire pdpending
this commit retires pdpending.
namely,
* stop counting it in kernel
* stop printing it in userland
* uvmexp/uvmexp_sysctl fields are left intact for compatibility
pdpending is documented in a few places:
uvm(9),uvm_extern.h: "number of times daemon got a pending pageout"
vmstat: "total pending pageouts"
but no one seems to know what it actually means.
here's my reasearch:
in 1998, uvm was imported to our tree.
("initial import of the new virtual memory system, UVM, into
-current.") if my reading of the ancient version of uvm is
[60 lines not shown] doc/TODO: add some
+ dasel-3.4.0, dunst-1.13.2, ghostscript-agpl-10.07.0, git-delta-0.19.0,
harfbuzz-13.2.1, icu-78.3, jjui-0.10.2, jsoncpp-1.9.7, libavif-1.4.1,
libde265-1.0.18, libfyaml-0.9.6, libzim-9.5.1, lowdown-3.0.1,
meson-1.10.2, ocaml-dune-3.22.0, openexr-3.4.7, protobuf-34.1,
py-attrs-26.1.0, py-charset-normalizer-3.4.6, py-coverage-7.13.5,
py-cyclonedx-python-lib-11.7.0, py-google-api-python-client-2.193.0,
py-importlib-metadata-9.0.0, py-jaraco.context-6.1.2,
py-protobuf-7.34.1, py-pygls-2.1.0, py-ruff-0.15.7,
py-sphinx-autodoc-typehints-3.9.9, py-test-cov-7.1.0,
py-uv-build-0.10.12, rumdl-0.1.57 [needs rust 1.94], slumber-5.2.0,
syncstorage-rs-0.22.0, tree-sitter-rust-0.24.1.