On 9/5/25 11:38 AM, Tom Tromey wrote:
>>>>>> "Kevin" == Kevin Buettner <kevinb@redhat.com> writes:
> 
> Kevin>   This version 2 commit
> Kevin> adds that by making DW_TAG_subprogram declarations "interesting" to
> Kevin> the indexer.  The changes which do this are in gdb/dwarf2/abbrev.c
> Kevin> and gdb/dwarf2/cooked-indexer.c.
> 
> I have some questions about this change.
> 
> How many symbols does it add, and what performance impact does it have?
> I tend to think the indexer is fast primarily because it skips DIEs, but
> IIUC this will have it read many more.

To measure this, I do:

$ ./gdb -nx -q --data-directory=data-directory -ex 'maint set dwarf sync on' -ex 'maintenance set per-command time on'

Then, use the "file" command.

For example, I ran gdb on libxul.so.debug without and with this patch
applied, see the two attached files.

The longest "DWARF indexing worker" step went from

  wall 0.668, user 0.574, sys 0.093, user+sys 0.667, 99.9 % CPU

to

  wall 0.792, user 0.664, sys 0.124, user+sys 0.788, 99.5 % CPU

The longest "DWARF finalize worker" step went from

  wall 1.691, user 1.687, sys 0.003, user+sys 1.690, 99.9 % CPU

to

  wall 3.650, user 3.626, sys 0.008, user+sys 3.634, 99.6 % CPU

The complete file command went from

  13.375465 (cpu), 3.019934 (wall)

to

  23.984434 (cpu), 5.163825 (wall)

Simon