From: Taylor Blau <me@ttaylorr.com>
To: Jonathan Tan <jonathantanmy@google.com>
Cc: me@ttaylorr.com, git@vger.kernel.org, dstolee@microsoft.com,
gitster@pobox.com, peff@peff.net, martin.agren@gmail.com,
szeder.dev@gmail.com
Subject: Re: [PATCH v2 12/24] pack-bitmap-write: fill bitmap with commit history
Date: Sat, 28 Nov 2020 12:21:20 -0500 [thread overview]
Message-ID: <X8KHEMl87sU5cIGK@nand.local> (raw)
In-Reply-To: <20201125011409.941639-1-jonathantanmy@google.com>
On Tue, Nov 24, 2020 at 05:14:09PM -0800, Jonathan Tan wrote:
> > From: Derrick Stolee <dstolee@microsoft.com>
> >
> > The fill_bitmap_commit() method assumes that every parent of the given
> > commit is already part of the current bitmap. Instead of making that
> > assumption, let's walk parents until we reach commits already part of
> > the bitmap. Set the value for that parent immediately after querying to
> > save time doing double calls to find_object_pos() and to avoid inserting
> > the parent into the queue multiple times.
>
> I see from the later patches that this has no effect until the part
> where we can skip commits, but as Junio says [1], it's worth mentioning
> it here. Maybe something like:
>
> The fill_bitmap_commit() method assumes that every parent of the given
> commit is already part of the current bitmap. This is currently
> correct, but a subsequent patch will change the nature of the edges of
> the graph from parent-child to ancestor-descendant. In preparation for
> that, let's walk parents...
Thanks. Stolee and I worked a little on revising this last week, and I
think that the current log message is more along these lines. Here's
what we wrote:
pack-bitmap-write: fill bitmap with commit history
The current implementation of bitmap_writer_build() creates a
reachability bitmap for every walked commit. After computing a bitmap
for a commit, those bits are pushed to an in-progress bitmap for its
children.
fill_bitmap_commit() assumes the bits corresponding to objects
reachable from the parents of a commit are already set. This means that
when visiting a new commit, we only have to walk the objects reachable
between it and any of its parents.
A future change to bitmap_writer_build() will relax this condition so
not all parents have their reachable objects set in the in-progress
bitmap. Prepare for that by having 'fill_bitmap_commit()' walk
parents until reaching commits whose bits are already set. Then, walk
the trees for these commits as well.
This has no functional change with the current implementation of
bitmap_writer_build().
> > static void fill_bitmap_commit(struct bb_commit *ent,
> > - struct commit *commit)
> > + struct commit *commit,
> > + struct prio_queue *queue)
>
> As far as I can see, this function expects an empty queue and always
> ends with the queue empty, and the only reason why we don't instantiate
> a new queue every time is so that we can save on the internal array
> allocation/deallocation. Maybe add a comment to that effect.
Sure. Would you find a comment like that more helpful above
'fill_bitmap_commit()', or above the declaration of 'queue' (in
'bitmap_writer_build()') itself?
Thanks,
Taylor
next prev parent reply other threads:[~2020-11-28 22:55 UTC|newest]
Thread overview: 173+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-11 19:41 [PATCH 00/23] pack-bitmap: bitmap generation improvements Taylor Blau
2020-11-11 19:41 ` [PATCH 01/23] ewah/ewah_bitmap.c: grow buffer past 1 Taylor Blau
2020-11-22 19:36 ` Junio C Hamano
2020-11-23 16:22 ` Taylor Blau
2020-11-24 2:48 ` Jeff King
2020-11-24 2:51 ` Jeff King
2020-12-01 22:56 ` Taylor Blau
2020-11-11 19:41 ` [PATCH 02/23] pack-bitmap: fix header size check Taylor Blau
2020-11-12 17:39 ` Martin Ågren
2020-11-11 19:42 ` [PATCH 03/23] pack-bitmap: bounds-check size of cache extension Taylor Blau
2020-11-12 17:47 ` Martin Ågren
2020-11-13 4:57 ` Jeff King
2020-11-13 5:26 ` Martin Ågren
2020-11-13 21:29 ` Taylor Blau
2020-11-13 21:39 ` Jeff King
2020-11-13 21:49 ` Taylor Blau
2020-11-13 22:11 ` Jeff King
2020-11-11 19:42 ` [PATCH 04/23] t5310: drop size of truncated ewah bitmap Taylor Blau
2020-11-11 19:42 ` [PATCH 05/23] rev-list: die when --test-bitmap detects a mismatch Taylor Blau
2020-11-11 19:42 ` [PATCH 06/23] ewah: factor out bitmap growth Taylor Blau
2020-11-11 19:42 ` [PATCH 07/23] ewah: make bitmap growth less aggressive Taylor Blau
2020-11-22 20:32 ` Junio C Hamano
2020-11-23 16:49 ` Taylor Blau
2020-11-24 3:00 ` Jeff King
2020-11-24 20:11 ` Junio C Hamano
2020-11-11 19:43 ` [PATCH 08/23] ewah: implement bitmap_or() Taylor Blau
2020-11-22 20:34 ` Junio C Hamano
2020-11-23 16:52 ` Taylor Blau
2020-11-11 19:43 ` [PATCH 09/23] ewah: add bitmap_dup() function Taylor Blau
2020-11-11 19:43 ` [PATCH 10/23] pack-bitmap-write: reimplement bitmap writing Taylor Blau
2020-11-11 19:43 ` [PATCH 11/23] pack-bitmap-write: pass ownership of intermediate bitmaps Taylor Blau
2020-11-11 19:43 ` [PATCH 12/23] pack-bitmap-write: fill bitmap with commit history Taylor Blau
2020-11-11 19:43 ` [PATCH 13/23] bitmap: add bitmap_diff_nonzero() Taylor Blau
2020-11-11 19:43 ` [PATCH 14/23] commit: implement commit_list_contains() Taylor Blau
2020-11-11 19:43 ` [PATCH 15/23] t5310: add branch-based checks Taylor Blau
2020-11-11 20:58 ` Derrick Stolee
2020-11-11 21:04 ` Junio C Hamano
2020-11-15 23:26 ` Johannes Schindelin
2020-11-11 19:43 ` [PATCH 16/23] pack-bitmap-write: rename children to reverse_edges Taylor Blau
2020-11-11 19:43 ` [PATCH 17/23] pack-bitmap-write: build fewer intermediate bitmaps Taylor Blau
2020-11-13 22:23 ` SZEDER Gábor
2020-11-13 23:03 ` Jeff King
2020-11-14 6:23 ` Jeff King
2020-11-11 19:43 ` [PATCH 18/23] pack-bitmap-write: ignore BITMAP_FLAG_REUSE Taylor Blau
2020-11-11 19:44 ` [PATCH 19/23] pack-bitmap: factor out 'bitmap_for_commit()' Taylor Blau
2020-11-11 19:44 ` [PATCH 20/23] pack-bitmap: factor out 'add_commit_to_bitmap()' Taylor Blau
2020-11-11 19:44 ` [PATCH 21/23] pack-bitmap-write: use existing bitmaps Taylor Blau
2020-11-11 19:44 ` [PATCH 22/23] pack-bitmap-write: relax unique rewalk condition Taylor Blau
2020-11-11 19:44 ` [PATCH 23/23] pack-bitmap-write: better reuse bitmaps Taylor Blau
2020-11-17 21:46 ` [PATCH v2 00/24] pack-bitmap: bitmap generation improvements Taylor Blau
2020-11-17 21:46 ` [PATCH v2 01/24] ewah/ewah_bitmap.c: grow buffer past 1 Taylor Blau
2020-11-17 21:46 ` [PATCH v2 02/24] pack-bitmap: fix header size check Taylor Blau
2020-11-17 21:46 ` [PATCH v2 03/24] pack-bitmap: bounds-check size of cache extension Taylor Blau
2020-11-17 21:46 ` [PATCH v2 04/24] t5310: drop size of truncated ewah bitmap Taylor Blau
2020-11-17 21:46 ` [PATCH v2 05/24] rev-list: die when --test-bitmap detects a mismatch Taylor Blau
2020-11-17 21:46 ` [PATCH v2 06/24] ewah: factor out bitmap growth Taylor Blau
2020-11-17 21:47 ` [PATCH v2 07/24] ewah: make bitmap growth less aggressive Taylor Blau
2020-11-17 21:47 ` [PATCH v2 08/24] ewah: implement bitmap_or() Taylor Blau
2020-11-17 21:47 ` [PATCH v2 09/24] ewah: add bitmap_dup() function Taylor Blau
2020-11-17 21:47 ` [PATCH v2 10/24] pack-bitmap-write: reimplement bitmap writing Taylor Blau
2020-11-25 0:53 ` Jonathan Tan
2020-11-28 17:27 ` Taylor Blau
2020-11-17 21:47 ` [PATCH v2 11/24] pack-bitmap-write: pass ownership of intermediate bitmaps Taylor Blau
2020-11-25 1:00 ` Jonathan Tan
2020-11-17 21:47 ` [PATCH v2 12/24] pack-bitmap-write: fill bitmap with commit history Taylor Blau
2020-11-22 21:50 ` Junio C Hamano
2020-11-23 14:54 ` Derrick Stolee
2020-11-25 1:14 ` Jonathan Tan
2020-11-28 17:21 ` Taylor Blau [this message]
2020-11-30 18:33 ` Jonathan Tan
2020-11-17 21:47 ` [PATCH v2 13/24] bitmap: add bitmap_diff_nonzero() Taylor Blau
2020-11-22 22:01 ` Junio C Hamano
2020-11-23 20:19 ` Taylor Blau
2020-11-17 21:47 ` [PATCH v2 14/24] commit: implement commit_list_contains() Taylor Blau
2020-11-17 21:47 ` [PATCH v2 15/24] t5310: add branch-based checks Taylor Blau
2020-11-25 1:17 ` Jonathan Tan
2020-11-28 17:30 ` Taylor Blau
2020-11-17 21:47 ` [PATCH v2 16/24] pack-bitmap-write: rename children to reverse_edges Taylor Blau
2020-11-17 21:47 ` [PATCH v2 17/24] pack-bitmap.c: check reads more aggressively when loading Taylor Blau
2020-11-17 21:48 ` [PATCH v2 18/24] pack-bitmap-write: build fewer intermediate bitmaps Taylor Blau
2020-11-24 6:07 ` Jonathan Tan
2020-11-25 1:46 ` Jonathan Tan
2020-11-30 18:41 ` Derrick Stolee
2020-11-17 21:48 ` [PATCH v2 19/24] pack-bitmap-write: ignore BITMAP_FLAG_REUSE Taylor Blau
2020-12-02 7:13 ` Jonathan Tan
2020-11-17 21:48 ` [PATCH v2 20/24] pack-bitmap: factor out 'bitmap_for_commit()' Taylor Blau
2020-12-02 7:17 ` Jonathan Tan
2020-11-17 21:48 ` [PATCH v2 21/24] pack-bitmap: factor out 'add_commit_to_bitmap()' Taylor Blau
2020-12-02 7:20 ` Jonathan Tan
2020-11-17 21:48 ` [PATCH v2 22/24] pack-bitmap-write: use existing bitmaps Taylor Blau
2020-12-02 7:28 ` Jonathan Tan
2020-12-02 16:21 ` Taylor Blau
2020-11-17 21:48 ` [PATCH v2 23/24] pack-bitmap-write: relax unique rewalk condition Taylor Blau
2020-12-02 7:44 ` Jonathan Tan
2020-12-02 16:30 ` Taylor Blau
2020-12-07 18:19 ` Jonathan Tan
2020-12-07 18:43 ` Derrick Stolee
2020-12-07 18:45 ` Derrick Stolee
2020-12-07 18:48 ` Jeff King
2020-11-17 21:48 ` [PATCH v2 24/24] pack-bitmap-write: better reuse bitmaps Taylor Blau
2020-12-02 8:08 ` Jonathan Tan
2020-12-02 16:35 ` Taylor Blau
2020-12-02 18:22 ` Derrick Stolee
2020-12-02 18:25 ` Taylor Blau
2020-12-07 18:26 ` Jonathan Tan
2020-12-07 18:24 ` Jonathan Tan
2020-12-07 19:20 ` Derrick Stolee
2020-11-18 18:32 ` [PATCH v2 00/24] pack-bitmap: bitmap generation improvements SZEDER Gábor
2020-11-18 19:51 ` Taylor Blau
2020-11-22 2:17 ` Taylor Blau
2020-11-22 2:28 ` Taylor Blau
2020-11-20 6:34 ` Martin Ågren
2020-11-21 19:37 ` Junio C Hamano
2020-11-21 20:11 ` Martin Ågren
2020-11-22 2:31 ` Taylor Blau
2020-11-24 2:43 ` Jeff King
2020-12-01 23:04 ` Taylor Blau
2020-12-01 23:37 ` Jonathan Tan
2020-12-01 23:43 ` Taylor Blau
2020-12-02 8:11 ` Jonathan Tan
2020-12-08 0:04 ` [PATCH v3 " Taylor Blau
2020-12-08 0:04 ` [PATCH v3 01/24] ewah/ewah_bitmap.c: avoid open-coding ALLOC_GROW() Taylor Blau
2020-12-08 0:04 ` [PATCH v3 02/24] pack-bitmap: fix header size check Taylor Blau
2020-12-08 0:04 ` [PATCH v3 03/24] pack-bitmap: bounds-check size of cache extension Taylor Blau
2020-12-08 0:04 ` [PATCH v3 04/24] t5310: drop size of truncated ewah bitmap Taylor Blau
2020-12-08 0:04 ` [PATCH v3 05/24] rev-list: die when --test-bitmap detects a mismatch Taylor Blau
2020-12-08 0:04 ` [PATCH v3 06/24] ewah: factor out bitmap growth Taylor Blau
2020-12-08 0:04 ` [PATCH v3 07/24] ewah: make bitmap growth less aggressive Taylor Blau
2020-12-08 0:04 ` [PATCH v3 08/24] ewah: implement bitmap_or() Taylor Blau
2020-12-08 0:04 ` [PATCH v3 09/24] ewah: add bitmap_dup() function Taylor Blau
2020-12-08 0:04 ` [PATCH v3 10/24] pack-bitmap-write: reimplement bitmap writing Taylor Blau
2020-12-08 0:05 ` [PATCH v3 11/24] pack-bitmap-write: pass ownership of intermediate bitmaps Taylor Blau
2020-12-08 0:05 ` [PATCH v3 12/24] pack-bitmap-write: fill bitmap with commit history Taylor Blau
2020-12-08 0:05 ` [PATCH v3 13/24] bitmap: implement bitmap_is_subset() Taylor Blau
2020-12-08 0:05 ` [PATCH v3 14/24] commit: implement commit_list_contains() Taylor Blau
2020-12-08 0:05 ` [PATCH v3 15/24] t5310: add branch-based checks Taylor Blau
2020-12-08 0:05 ` [PATCH v3 16/24] pack-bitmap-write: rename children to reverse_edges Taylor Blau
2020-12-08 0:05 ` [PATCH v3 17/24] pack-bitmap.c: check reads more aggressively when loading Taylor Blau
2020-12-08 0:05 ` [PATCH v3 18/24] pack-bitmap-write: build fewer intermediate bitmaps Taylor Blau
2020-12-08 0:05 ` [PATCH v3 19/24] pack-bitmap-write: ignore BITMAP_FLAG_REUSE Taylor Blau
2020-12-08 0:05 ` [PATCH v3 20/24] pack-bitmap: factor out 'bitmap_for_commit()' Taylor Blau
2020-12-08 0:05 ` [PATCH v3 21/24] pack-bitmap: factor out 'add_commit_to_bitmap()' Taylor Blau
2020-12-08 0:05 ` [PATCH v3 22/24] pack-bitmap-write: use existing bitmaps Taylor Blau
2020-12-08 0:05 ` [PATCH v3 23/24] pack-bitmap-write: relax unique rewalk condition Taylor Blau
2020-12-08 0:05 ` [PATCH v3 24/24] pack-bitmap-write: better reuse bitmaps Taylor Blau
2020-12-08 20:56 ` [PATCH v3 00/24] pack-bitmap: bitmap generation improvements Junio C Hamano
2020-12-08 21:03 ` Taylor Blau
2020-12-08 22:03 ` Junio C Hamano
2020-12-08 22:03 ` [PATCH v4 " Taylor Blau
2020-12-08 22:03 ` [PATCH v4 01/24] ewah/ewah_bitmap.c: avoid open-coding ALLOC_GROW() Taylor Blau
2020-12-08 22:03 ` [PATCH v4 02/24] pack-bitmap: fix header size check Taylor Blau
2020-12-08 22:03 ` [PATCH v4 03/24] pack-bitmap: bounds-check size of cache extension Taylor Blau
2020-12-08 22:03 ` [PATCH v4 04/24] t5310: drop size of truncated ewah bitmap Taylor Blau
2020-12-08 22:03 ` [PATCH v4 05/24] rev-list: die when --test-bitmap detects a mismatch Taylor Blau
2020-12-08 22:03 ` [PATCH v4 06/24] ewah: factor out bitmap growth Taylor Blau
2020-12-08 22:03 ` [PATCH v4 07/24] ewah: make bitmap growth less aggressive Taylor Blau
2020-12-08 22:03 ` [PATCH v4 08/24] ewah: implement bitmap_or() Taylor Blau
2020-12-08 22:03 ` [PATCH v4 09/24] ewah: add bitmap_dup() function Taylor Blau
2020-12-08 22:03 ` [PATCH v4 10/24] pack-bitmap-write: reimplement bitmap writing Taylor Blau
2020-12-08 22:03 ` [PATCH v4 11/24] pack-bitmap-write: pass ownership of intermediate bitmaps Taylor Blau
2020-12-08 22:04 ` [PATCH v4 12/24] pack-bitmap-write: fill bitmap with commit history Taylor Blau
2020-12-08 22:04 ` [PATCH v4 13/24] bitmap: implement bitmap_is_subset() Taylor Blau
2020-12-08 22:04 ` [PATCH v4 14/24] commit: implement commit_list_contains() Taylor Blau
2020-12-08 22:04 ` [PATCH v4 15/24] t5310: add branch-based checks Taylor Blau
2020-12-08 22:04 ` [PATCH v4 16/24] pack-bitmap-write: rename children to reverse_edges Taylor Blau
2020-12-08 22:04 ` [PATCH v4 17/24] pack-bitmap.c: check reads more aggressively when loading Taylor Blau
2020-12-08 22:04 ` [PATCH v4 18/24] pack-bitmap-write: build fewer intermediate bitmaps Taylor Blau
2020-12-08 22:04 ` [PATCH v4 19/24] pack-bitmap-write: ignore BITMAP_FLAG_REUSE Taylor Blau
2020-12-08 22:04 ` [PATCH v4 20/24] pack-bitmap: factor out 'bitmap_for_commit()' Taylor Blau
2020-12-08 22:05 ` [PATCH v4 21/24] pack-bitmap: factor out 'add_commit_to_bitmap()' Taylor Blau
2020-12-08 22:05 ` [PATCH v4 22/24] pack-bitmap-write: use existing bitmaps Taylor Blau
2020-12-08 22:05 ` [PATCH v4 23/24] pack-bitmap-write: relax unique revwalk condition Taylor Blau
2020-12-08 22:05 ` [PATCH v4 24/24] pack-bitmap-write: better reuse bitmaps Taylor Blau
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