[RFC,00/10] how to reclaim unneeded vmlinux memory ?

Message

Jim Cromie Oct. 12, 2023, 7:47 p.m. UTC

For builtin modules, dynamic-debug allocates blocks of memory into
DATA, via vmlinux.lds.h.

dyndbg's struct _ddebug has fields: modname, filename, function, which
keeps the the code's structural/organizational info used to enable &
prefix prdbg callsites.

The linker packs the callsites in-order, which means the repetition in
those 3 columns can be compactly encoded in non-overlapping intervals.

So this saves each unique column-val and its interval into a
maple-tree per column, and retrieves them as needed with accessors.

It also splits out _ddebug_site and __dyndbg_sites section, and no
longer needs the section, so that block is ready to reclaim.

Somethings wrong with patch-9, but it seems worth showing around.


Jim Cromie (10):
  dyndbg: prep to isolate 3 repetetive fields
  dyndbg: split __dyndbg_sites section out from __dyndbg
  dyndbg: add 2nd cursor pair to init-fn
  dyndbg: save _ddebug_site mod,file,func fields into maple-trees
  dyndbg: avoid _ddebug.site in ddebug_condense_sites
  dyndbg: add site_*() macros to avoid using _ddebug.site
  dyndbg: wire in __desc_*() functions
  dyndbg: drop _ddebug.site member
  dyndbg: add dd_clear_range to prune mtrees
  dyndbg: cache the dynamically generated prefixes per callsite

 include/asm-generic/vmlinux.lds.h |   1 +
 include/linux/dynamic_debug.h     |  40 +++--
 kernel/module/main.c              |   3 +
 lib/dynamic_debug.c               | 238 +++++++++++++++++++++++++++---
 4 files changed, 252 insertions(+), 30 deletions(-)