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From: Derrick Stolee <derrickstolee@github.com>
To: Taylor Blau <me@ttaylorr.com>
Cc: git@vger.kernel.org, Jeff King <peff@peff.net>,
	Junio C Hamano <gitster@pobox.com>
Subject: Re: [PATCH v2 0/2] pack-bitmap: boundary-based bitmap traversalt
Date: Fri, 5 May 2023 16:45:35 -0400	[thread overview]
Message-ID: <4ce3ff5f-e7cd-f604-f5da-66939be7d314@github.com> (raw)
In-Reply-To: <ZFVO9kFZ+lr32WxY@nand.local>



On 5/5/2023 2:46 PM, Taylor Blau wrote:
> On Fri, May 05, 2023 at 01:59:31PM -0400, Derrick Stolee wrote:
>> On 5/5/2023 1:27 PM, Taylor Blau wrote:
>>> Here is a reroll of my series to implement a boundary-based bitmap
>>> traversal algorithm that I worked on towards the end of 2021 with Peff.
>>>
>>> The algorithm is unchanged from the last version, but the implementation
>>> has been made much more straightforward, thanks to a very helpful
>>> suggestion from Stolee.
>>>
>>> Instead of hackily trying to write down all of the UNINTERESTING commits
>>> between the tips and boundary within limit_list(), we can just perform a
>>> commit-only walk, which will give us the set of commits that we need.
>>
>> Something that didn't seem to get attention in this version was buried
>> deep in the commentary of my high-level review [1]:
> 
> Oops, sorry, I definitely missed this unintentionally and did not mean
> to ignore it.

I had to dig deep to find it, even after knowing it was in there
somewhere, so I'm not upset it didn't happen this version.

>>> For these reasons, I'm surprised that this patch completely replaces
>>> the old algorithm for the new one. I would prefer to see a config
>>> option that enables this new algorithm. It would be safer to deploy
>>> that way, too.
>>
>> I still think it would be nice to keep the two algorithms for at least
>> a little while instead of completely removing the old one. Let's gather
>> some more evidence and get more reps in with the new algorithm before
>> making it the new default. I could imagine a scenario where someone
>> really wants to spend the extra time to make sure none of the objects
>> reachable from the UNINTERESTING commits are included in the output of
>> this diff.
>>
>> [1] https://lore.kernel.org/git/a143150d-7cf5-c697-0e48-0f7af1c6de8f@github.com/
> 
> Hmm. I'm not opposed to keeping the old algorithm around, though I
> wonder what the configuration option would look like here. I imagine
> that we don't want to support the old algorithm indefinitely, though.
> 
> Perhaps something like `pack.useBoundaryBitmapTraversal` (implied by
> `feature.experimental`), defaulting to "false", and then eventually
> "true"?

This name makes sense to me. Including it in feature.experimental right
away seems like a good idea. Incrementing it to "true" by default after
a single release would make sense, too, since the performance benefits
are so clear. Just important to have that emergency toggle.

Thanks,
-Stolee

  reply	other threads:[~2023-05-05 20:45 UTC|newest]

Thread overview: 51+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-04-25  0:00 [PATCH 0/3] pack-bitmap: boundary-based bitmap traversal Taylor Blau
2023-04-25  0:00 ` [PATCH 1/3] revision: support tracking uninteresting commits Taylor Blau
2023-04-25 18:15   ` Derrick Stolee
2023-05-03 21:48     ` Taylor Blau
2023-05-04 13:46       ` Derrick Stolee
2023-05-03 22:08     ` Taylor Blau
2023-05-04 13:59       ` Derrick Stolee
2023-05-05 17:30         ` Taylor Blau
2023-04-25 18:22   ` Junio C Hamano
2023-04-25 18:48     ` Taylor Blau
2023-04-25  0:00 ` [PATCH 2/3] pack-bitmap.c: extract `fill_in_bitmap()` Taylor Blau
2023-04-25 18:32   ` Junio C Hamano
2023-04-25 18:51     ` [PATCH 2/3] pack-bitmap.c: extract `fill_in_bitmap()`t Taylor Blau
2023-04-25  0:00 ` [PATCH 3/3] pack-bitmap.c: use commit boundary during bitmap traversal Taylor Blau
2023-04-25 18:52   ` Junio C Hamano
2023-05-02 21:31     ` Felipe Contreras
2023-05-03 21:42     ` Taylor Blau
2023-05-03 21:58       ` Junio C Hamano
2023-04-25 18:53   ` Derrick Stolee
2023-04-25 18:02 ` [PATCH 0/3] pack-bitmap: boundary-based " Junio C Hamano
2023-04-25 18:30   ` Derrick Stolee
2023-04-25 18:57     ` Taylor Blau
2023-04-25 19:52       ` Derrick Stolee
2023-05-03 21:43         ` Taylor Blau
2023-04-25 18:06 ` Derrick Stolee
2023-04-25 19:01   ` Taylor Blau
2023-04-25 20:27     ` Derrick Stolee
2023-05-01 22:08 ` Junio C Hamano
2023-05-02 23:52   ` Taylor Blau
2023-05-05 17:27 ` [PATCH v2 0/2] " Taylor Blau
2023-05-05 17:27   ` [PATCH v2 1/2] pack-bitmap.c: extract `fill_in_bitmap()` Taylor Blau
2023-05-05 17:27   ` [PATCH v2 2/2] pack-bitmap.c: use commit boundary during bitmap traversal Taylor Blau
2023-05-05 18:13     ` Derrick Stolee
2023-05-05 18:43       ` Taylor Blau
2023-05-05 17:33   ` [PATCH v2 0/2] pack-bitmap: boundary-based " Junio C Hamano
2023-05-05 17:59   ` Derrick Stolee
2023-05-05 18:46     ` [PATCH v2 0/2] pack-bitmap: boundary-based bitmap traversalt Taylor Blau
2023-05-05 20:45       ` Derrick Stolee [this message]
2023-05-08 17:38 ` [PATCH v3 0/3] pack-bitmap: boundary-based bitmap traversal Taylor Blau
2023-05-08 17:38   ` [PATCH v3 1/3] object: add object_array initializer helper function Taylor Blau
2023-05-08 17:38   ` [PATCH v3 2/3] pack-bitmap.c: extract `fill_in_bitmap()` Taylor Blau
2023-05-08 17:38   ` [PATCH v3 3/3] pack-bitmap.c: use commit boundary during bitmap traversal Taylor Blau
2023-05-08 20:53     ` Derrick Stolee
2023-05-08 22:12       ` Taylor Blau
2023-05-10 22:55   ` [PATCH v3 0/3] pack-bitmap: boundary-based " Junio C Hamano
2023-05-10 23:10     ` Taylor Blau
2023-05-11 15:23       ` Derrick Stolee
2023-06-08 16:25 ` [PATCH v4 " Taylor Blau
2023-06-08 16:25   ` [PATCH v4 1/3] object: add object_array initializer helper function Taylor Blau
2023-06-08 16:25   ` [PATCH v4 2/3] pack-bitmap.c: extract `fill_in_bitmap()` Taylor Blau
2023-06-08 16:25   ` [PATCH v4 3/3] pack-bitmap.c: use commit boundary during bitmap traversal Taylor Blau

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