From: Derrick Stolee <stolee@gmail.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 24/24] pack-bitmap-write: better reuse bitmaps
Date: Mon, 7 Dec 2020 14:20:54 -0500 [thread overview]
Message-ID: <1cd3f001-389f-6e2e-90fd-5e8b4b17119a@gmail.com> (raw)
In-Reply-To: <20201207182418.3034961-1-jonathantanmy@google.com>
On 12/7/2020 1:24 PM, Jonathan Tan wrote:
>> On 12/2/2020 11:35 AM, Taylor Blau wrote:
>>> On Wed, Dec 02, 2020 at 12:08:08AM -0800, Jonathan Tan wrote:
>>>>> + c_ent->maximal = 1;
>>>>> + p = NULL;
>>>>
>>>> Here, we're setting maximal without also setting a bit in this commit's
>>>> commit_mask. This is fine because we're not propagating this commit's
>>>> commit_mask to any parents (we're not continuing the walk from this
>>>> commit), but it seems like a code smell. Suggested fix is below.
>>>>
>>>>> + }
>>>>> +
>>>>> if (c_ent->maximal) {
>>>>> num_maximal++;
>>>>> ALLOC_GROW(bb->commits, bb->commits_nr + 1, bb->commits_alloc);
>>>>> bb->commits[bb->commits_nr++] = commit;
>>>>> }
>>>>
>>>> As far as I can tell, this means that this commit occupies a bit
>>>> position in the commit mask that it doesn't need. Could this go into a
>>>> separate list instead, to be appended to bb->commits at the very end?
>>
>> I don't see any value in having a second list here. That only makes
>> things more complicated.
>
> It does make things more complicated, but it could help shrink commit
> bitmasks (which seem to be a concern, according to patch 23).
>
> Suppose num_maximal was 3 and we encountered such a commit (not
> selected, but has an old bitmap). So we increment num_maximal. Then, we
> encounter a selected commit. That commit would then have a bitmask of
> ???01. If we had not incremented num_maximal (which would require a
> second list), then the bitmask would be ???1.
OK, I see the value. The value is bounded, since the number of
these "0" gaps is bounded by the number of selected commits _and_
reduces the possible number of maximal commits.
However, that seems like enough justification to create the second
list.
Thanks,
-Stolee
next prev parent reply other threads:[~2020-12-07 19:21 UTC|newest]
Thread overview: 174+ 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
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 [this message]
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 ` 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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