[PATCH] pack-objects.h: remove outdated pahole results

The size and padding of `struct object_entry` is an important factor in determining the memory usage of `pack-objects`. For this reason, 3b13a5f263 (pack-objects: reorder members to shrink struct object_entry, 2018-04-14) added a comment containing some information from pahole indicating the size and padding of that struct.

Unfortunately, this comment hasn't been updated since 9ac3f0e5b3 (pack-objects: fix performance issues on packing large deltas, 2018-07-22), despite the size of this struct changing many times since that commit.

To see just how often the size of object_entry changes, I skimmed the first-parent history with this script:

    for sha in $(git rev-list --first-parent --reverse 9ac3f0e..)
    do
      echo -n "$sha "
      git checkout -q $sha
      make -s pack-objects.o 2>/dev/null
      pahole -C object_entry pack-objects.o | sed -n \
        -e 's/\/\* size: \([0-9]*\).*/size \1/p' \
        -e 's/\/\*.*padding: \([0-9]*\).*/padding \1/p' | xargs
    done | uniq -f1

In between each merge, the size of object_entry changes too often to record every instance here. But the important merges (along with their corresponding sizes and bit paddings) in chronological order are:

    ad635e82d6 (Merge branch 'nd/pack-objects-pack-struct', 2018-05-23) size 80 padding 4
    29d9e3e2c4 (Merge branch 'nd/pack-deltify-regression-fix', 2018-08-22) size 80 padding 9
    3ebdef2e1b (Merge branch 'jk/pack-delta-reuse-with-bitmap', 2018-09-17) size 80 padding 8
    33e4ae9c50 (Merge branch 'bc/sha-256', 2019-01-29) size 96 padding 8

(indicating that the current size of the struct is 96 bytes, with 8 padding bits).

Even though this comment was written in a good spirit, it is updated infrequently enough that is serves to confuse rather than to encourage contributors to update the appropriate values when the modify the definition of object_entry.

For that reason, eliminate the confusion by removing the comment altogether.

Signed-off-by: Taylor Blau <me@ttaylorr.com>
---
Noticed this while reverting an old topic out of GitHub's fork, and
realized that this comment was severely out-of-date.

 pack-objects.h | 10 ----------
 1 file changed, 10 deletions(-)