"make delete-old" performance.
bf1783 at googlemail.com
Thu May 17 03:18:47 UTC 2012
> I recently ran "make delete-old" on a -current box and felt it was
> rather slow. That prompted me to do some more careful experiments.
> On one box where I have both 8-stable and 9-stable available, there
> was a ~30x slowdown (based on 5 runs, ignoring the first). I don't
> have a -current world on that box so I can't directly compare but on
> another pair of fairly similar boxes, I get a ~180x slowdown between
> 8-stable and -current (and that figure is probably optimistic since
> the -current box was idle whereas the 8-stable box was fairly busy).
> I realise that "make delete-old" isn't something you nede to do every
> day but going from sub-second to multi-minute duration is quite
> noticable. Can anyone suggest what has caused the change?
The slowdown is probably due - at least in part - to two factors:
- the list of files to be checked for removal has grown substantially,
because missing entries for old knobs and new entries for new knobs
have been added; and
- a new (and slower) method of checking was added in:
because the old method broke down with the size of the new lists of files.
Some changes could be made to lessen the affect of the latter.
More information about the freebsd-current