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From: Jeff King <peff@peff.net>
To: "SZEDER Gábor" <szeder.dev@gmail.com>
Cc: Rafael Silva <rafaeloliveira.cs@gmail.com>,
	Jonathan Tan <jonathantanmy@google.com>,
	Git Mailing List <git@vger.kernel.org>
Subject: [PATCH 0/3] low-hanging performance fruit with promisor packs
Date: Tue, 13 Apr 2021 03:12:54 -0400	[thread overview]
Message-ID: <YHVECXHfZ1bidTJH@coredump.intra.peff.net> (raw)
In-Reply-To: <YHTcHY+P7RuZJGab@coredump.intra.peff.net>

On Mon, Apr 12, 2021 at 07:47:41PM -0400, Jeff King wrote:

> The patch below drops the peak heap to 165MB. Still quite a bit more,
> but I think it's a combination of delta-base cache (96MB) plus extra
> structs for all the non-commit objects whose flags we marked.

I think we can do even better than that, after looking into the "do we
really need to parse the objects?" comment I left (spoiler: the answer
is no, we do not need to, at least for that caller).

Here are some cleaned-up patches that I think improve the situation
quite a bit. This is just the low-hanging fruit from this part of the
discussion; I'm sure there's more to do to make using partial clones
pleasant. In particular:

  - this does nothing for the "oops, we turned all of the promisor
    objects loose and then deleted them" problem. Hopefully Rafael
    will produce a nice patch for that

  - In is_promisor_object(), we still call parse_object(), because it
    really does look at the contents. But doing so for blobs is wasteful
    (it's a lot of bytes we push through sha1, and we don't even look at
    them). It might be worth using oid_object_info() to avoid this. This
    introduces a little overhead, but I think would be a net win (it
    would be really nice if we could amortize the object lookup work;
    i.e., if there was a way to call oid_object_info_extended() and say
    "open the object and look at the type; only return the contents if
    it's a non-blob").

  - I still think it's probably worth having a mode where we store the
    set of pointed-to objects we don't have, rather than parsing on the
    fly. This could easily be made optional (it's a good thing if you
    _have_ a lot of objects that point to a small or moderate number of
    missing objects, like a blob:limit or blob:none filter; it's a bad
    thing if you have very few objects but they point to a very large
    number).

I didn't explore any of those here, and I don't plan to look into them
anytime soon. I'm just documenting my findings for later.

Anyway, here are the patches.

  [1/3]: is_promisor_object(): free tree buffer after parsing
  [2/3]: lookup_unknown_object(): take a repository argument
  [3/3]: revision: avoid parsing with --exclude-promisor-objects

 builtin/fsck.c                   |  2 +-
 builtin/pack-objects.c           |  2 +-
 http-push.c                      |  2 +-
 object.c                         |  7 +++----
 object.h                         |  2 +-
 packfile.c                       |  1 +
 refs.c                           |  2 +-
 revision.c                       |  2 +-
 t/helper/test-example-decorate.c |  6 +++---
 t/perf/p5600-partial-clone.sh    | 12 ++++++++++++
 upload-pack.c                    |  2 +-
 walker.c                         |  2 +-
 12 files changed, 27 insertions(+), 15 deletions(-)

-Peff

  reply	other threads:[~2021-04-13  7:13 UTC|newest]

Thread overview: 46+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-04-03  9:04 rather slow 'git repack' in 'blob:none' partial clones SZEDER Gábor
2021-04-05  1:02 ` Rafael Silva
2021-04-07 21:17   ` Jeff King
2021-04-08  0:02     ` Jonathan Tan
2021-04-08  0:35       ` Jeff King
2021-04-12  7:09     ` Rafael Silva
2021-04-12 21:36     ` SZEDER Gábor
2021-04-12 21:49       ` Bryan Turner
2021-04-12 23:51         ` Jeff King
2021-04-12 23:47       ` Jeff King
2021-04-13  7:12         ` Jeff King [this message]
2021-04-13  7:15           ` [PATCH 1/3] is_promisor_object(): free tree buffer after parsing Jeff King
2021-04-13 20:17             ` Junio C Hamano
2021-04-14  5:18               ` Jeff King
2021-04-13  7:16           ` [PATCH 2/3] lookup_unknown_object(): take a repository argument Jeff King
2021-04-13  7:17           ` [PATCH 3/3] revision: avoid parsing with --exclude-promisor-objects Jeff King
2021-04-13 20:22             ` Junio C Hamano
2021-04-13 18:10           ` [PATCH 0/3] low-hanging performance fruit with promisor packs SZEDER Gábor
2021-04-14 17:14           ` Jonathan Tan
2021-04-14 19:22           ` Rafael Silva
2021-04-13 18:05         ` rather slow 'git repack' in 'blob:none' partial clones SZEDER Gábor
2021-04-14  5:14           ` Jeff King
2021-04-11 10:59   ` SZEDER Gábor
2021-04-12  7:53     ` Rafael Silva
2021-04-14 19:14 ` [PATCH 0/2] prevent `repack` to unpack and delete promisor objects Rafael Silva
2021-04-14 19:14   ` [PATCH 1/2] repack: teach --no-prune-packed to skip `git prune-packed` Rafael Silva
2021-04-14 23:50     ` Jonathan Tan
2021-04-18 14:15       ` Rafael Silva
2021-04-14 19:14   ` [PATCH 2/2] repack: avoid loosening promisor pack objects in partial clones Rafael Silva
2021-04-15  1:04     ` Jonathan Tan
2021-04-15  3:51       ` Junio C Hamano
2021-04-15  9:03         ` Jeff King
2021-04-15  9:05       ` Jeff King
2021-04-18  7:12       ` Rafael Silva
2021-04-15 18:06     ` Junio C Hamano
2021-04-18  8:40       ` Rafael Silva
2021-04-14 22:10   ` [PATCH 0/2] prevent `repack` to unpack and delete promisor objects Junio C Hamano
2021-04-15  9:15   ` Jeff King
2021-04-18  8:20     ` Rafael Silva
2021-04-18 13:57   ` [PATCH v2 0/1] " Rafael Silva
2021-04-18 13:57     ` [PATCH v2 1/1] repack: avoid loosening promisor objects in partial clones Rafael Silva
2021-04-19 19:15       ` Jonathan Tan
2021-04-21 18:54         ` Rafael Silva
2021-04-19 23:09       ` Junio C Hamano
2021-04-21 19:25         ` Rafael Silva
2021-04-21 19:32     ` [PATCH v3] " Rafael Silva

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