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From: Derrick Stolee <stolee@gmail.com>
To: Stefan Beller <sbeller@google.com>, gitgitgadget@gmail.com
Cc: git <git@vger.kernel.org>, "Jeff King" <peff@peff.net>,
	"Ævar Arnfjörð Bjarmason" <avarab@gmail.com>,
	"Jonathan Nieder" <jrnieder@gmail.com>,
	"Junio C Hamano" <gitster@pobox.com>,
	"Derrick Stolee" <dstolee@microsoft.com>
Subject: Re: [PATCH 3/5] pack-objects: add --sparse option
Date: Thu, 29 Nov 2018 09:20:29 -0500
Message-ID: <1e9d4d2d-561e-fcbc-48cf-374dcb9ce009@gmail.com> (raw)
In-Reply-To: <CAGZ79kbVGyX=Ky9HvmUGWPoHdLJYqnPTNda2kT3aC8XuHnH3+A@mail.gmail.com>

On 11/28/2018 5:11 PM, Stefan Beller wrote:
>> +--sparse::
>> +       Use the "sparse" algorithm to determine which objects to include in
>> +       the pack. This can have significant performance benefits when computing
>> +       a pack to send a small change. However, it is possible that extra
>> +       objects are added to the pack-file if the included commits contain
>> +       certain types of direct renames.
> As a user, where do I find a discussion of these walking algorithms?
> (i.e. how can I tell if I can really expect to gain performance benefits,
> what are the tradeoffs? "If it were strictly better than the original,
> it would be on by default" might be a thought of a user)

You're right that having this hidden as an opt-in config variable makes 
it hard to discover as a typical user.

I would argue that we should actually make the config setting true by 
default, and recommend that servers opt-out. Here are my reasons:

1. The vast majority of users are clients.

2. Client users are not likely to know about and tweak these settings.

3. Server users are more likely to keep an eye on the different knobs 
they can tweak.

4. Servers should use the reachability bitmaps, which don't use this 
logic anyway.

While _eventually_ we should make this opt-out, we shouldn't do that 
until it has cooked a while.

Thanks,
-Stolee

  reply index

Thread overview: 51+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-11-28 21:52 [PATCH 0/5] Add a new "sparse" tree walk algorithm Derrick Stolee via GitGitGadget
2018-11-28 21:52 ` [PATCH 1/5] revision: add mark_tree_uninteresting_sparse Derrick Stolee via GitGitGadget
2018-11-28 21:52 ` [PATCH 2/5] list-objects: consume sparse tree walk Derrick Stolee via GitGitGadget
2018-11-28 21:52 ` [PATCH 3/5] pack-objects: add --sparse option Derrick Stolee via GitGitGadget
2018-11-28 22:11   ` Stefan Beller
2018-11-29 14:20     ` Derrick Stolee [this message]
2018-11-30  2:39       ` Junio C Hamano
2018-11-30 15:53         ` Derrick Stolee
2018-11-28 21:52 ` [PATCH 4/5] revision: implement sparse algorithm Derrick Stolee via GitGitGadget
2018-11-28 21:52 ` [PATCH 5/5] pack-objects: create pack.useSparse setting Derrick Stolee via GitGitGadget
2018-11-28 22:18 ` [PATCH 0/5] Add a new "sparse" tree walk algorithm Ævar Arnfjörð Bjarmason
2018-11-29  4:05   ` Derrick Stolee
2018-11-29 14:24 ` [PATCH v2 0/6] " Derrick Stolee via GitGitGadget
2018-11-29 14:24   ` [PATCH v2 1/6] revision: add mark_tree_uninteresting_sparse Derrick Stolee via GitGitGadget
2018-11-29 14:24   ` [PATCH v2 2/6] list-objects: consume sparse tree walk Derrick Stolee via GitGitGadget
2018-11-29 14:24   ` [PATCH v2 3/6] pack-objects: add --sparse option Derrick Stolee via GitGitGadget
2018-11-29 14:24   ` [PATCH v2 4/6] revision: implement sparse algorithm Derrick Stolee via GitGitGadget
2018-11-29 14:24   ` [PATCH v2 5/6] pack-objects: create pack.useSparse setting Derrick Stolee via GitGitGadget
2018-11-29 14:24   ` [PATCH v2 6/6] pack-objects: create GIT_TEST_PACK_SPARSE Derrick Stolee via GitGitGadget
2018-12-10 16:42   ` [PATCH v3 0/6] Add a new "sparse" tree walk algorithm Derrick Stolee via GitGitGadget
2018-12-10 16:42     ` [PATCH v3 1/6] revision: add mark_tree_uninteresting_sparse Derrick Stolee via GitGitGadget
2018-12-10 16:42     ` [PATCH v3 2/6] list-objects: consume sparse tree walk Derrick Stolee via GitGitGadget
2018-12-10 16:42     ` [PATCH v3 3/6] pack-objects: add --sparse option Derrick Stolee via GitGitGadget
2018-12-10 16:42     ` [PATCH v3 4/6] revision: implement sparse algorithm Derrick Stolee via GitGitGadget
2018-12-10 16:42     ` [PATCH v3 5/6] pack-objects: create pack.useSparse setting Derrick Stolee via GitGitGadget
2018-12-10 16:42     ` [PATCH v3 6/6] pack-objects: create GIT_TEST_PACK_SPARSE Derrick Stolee via GitGitGadget
2018-12-14 21:22     ` [PATCH v4 0/6] Add a new "sparse" tree walk algorithm Derrick Stolee via GitGitGadget
2018-12-14 21:22       ` [PATCH v4 1/6] revision: add mark_tree_uninteresting_sparse Derrick Stolee via GitGitGadget
2019-01-11 19:43         ` Junio C Hamano
2019-01-11 20:25           ` Junio C Hamano
2019-01-11 22:05             ` Derrick Stolee
2018-12-14 21:22       ` [PATCH v4 2/6] list-objects: consume sparse tree walk Derrick Stolee via GitGitGadget
2019-01-11 23:20         ` Junio C Hamano
2018-12-14 21:22       ` [PATCH v4 3/6] pack-objects: add --sparse option Derrick Stolee via GitGitGadget
2019-01-11 22:30         ` Junio C Hamano
2019-01-15 15:06           ` Derrick Stolee
2019-01-15 18:23             ` Junio C Hamano
2018-12-14 21:22       ` [PATCH v4 4/6] revision: implement sparse algorithm Derrick Stolee via GitGitGadget
2018-12-14 23:32         ` Ævar Arnfjörð Bjarmason
2018-12-17 14:20           ` Derrick Stolee
2018-12-17 14:26             ` Ævar Arnfjörð Bjarmason
2018-12-17 14:50               ` Derrick Stolee
2019-01-11 23:20         ` Junio C Hamano
2018-12-14 21:22       ` [PATCH v4 5/6] pack-objects: create pack.useSparse setting Derrick Stolee via GitGitGadget
2018-12-14 21:22       ` [PATCH v4 6/6] pack-objects: create GIT_TEST_PACK_SPARSE Derrick Stolee via GitGitGadget
2019-01-16 18:25       ` [PATCH v5 0/5] Add a new "sparse" tree walk algorithm Derrick Stolee via GitGitGadget
2019-01-16 18:25         ` [PATCH v5 2/5] list-objects: consume sparse tree walk Derrick Stolee via GitGitGadget
2019-01-16 18:25         ` [PATCH v5 1/5] revision: add mark_tree_uninteresting_sparse Derrick Stolee via GitGitGadget
2019-01-16 18:25         ` [PATCH v5 3/5] revision: implement sparse algorithm Derrick Stolee via GitGitGadget
2019-01-16 18:26         ` [PATCH v5 4/5] pack-objects: create pack.useSparse setting Derrick Stolee via GitGitGadget
2019-01-16 18:26         ` [PATCH v5 5/5] pack-objects: create GIT_TEST_PACK_SPARSE Derrick Stolee via GitGitGadget

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