From: Jeff King <peff@peff.net>
To: Taylor Blau <me@ttaylorr.com>
Cc: git@vger.kernel.org, dstolee@microsoft.com, gitster@pobox.com
Subject: Re: [PATCH v2 6/8] builtin/pack-objects.c: rewrite honor-pack-keep logic
Date: Wed, 17 Feb 2021 11:05:22 -0500 [thread overview]
Message-ID: <YC0+wlRksoqm0xLO@coredump.intra.peff.net> (raw)
In-Reply-To: <c3868c7df92484f0527ce500ad1156275be334e8.1612411124.git.me@ttaylorr.com>
On Wed, Feb 03, 2021 at 10:59:17PM -0500, Taylor Blau wrote:
> @@ -1209,22 +1210,73 @@ static int want_found_object(int exclude, struct packed_git *p)
> * Otherwise, we signal "-1" at the end to tell the caller that we do
> * not know either way, and it needs to check more packs.
> */
> - if (!ignore_packed_keep_on_disk &&
> - !ignore_packed_keep_in_core &&
> - (!local || !have_non_local_packs))
> +
> + /*
> + * Handle .keep first, as we have a fast(er) path there.
> + */
> + if (ignore_packed_keep_on_disk || ignore_packed_keep_in_core) {
> + /*
> + * Set the flags for the kept-pack cache to be the ones we want
> + * to ignore.
> + *
> + * That is, if we are ignoring objects in on-disk keep packs,
> + * then we want to search through the on-disk keep and ignore
> + * the in-core ones.
> + */
> + unsigned flags = 0;
> + if (ignore_packed_keep_on_disk)
> + flags |= ON_DISK_KEEP_PACKS;
> + if (ignore_packed_keep_in_core)
> + flags |= IN_CORE_KEEP_PACKS;
> +
> + if (ignore_packed_keep_on_disk && p->pack_keep)
> + return 0;
> + if (ignore_packed_keep_in_core && p->pack_keep_in_core)
> + return 0;
> + if (has_object_kept_pack(oid, flags))
> + return 0;
> + }
> +
> + /*
> + * At this point we know definitively that either we don't care about
> + * keep-packs, or the object is not in one. Keep checking other
> + * conditions...
> + */
> +
> + if (!local || !have_non_local_packs)
> return 1;
> -
> if (local && !p->pack_local)
> return 0;
> - if (p->pack_local &&
> - ((ignore_packed_keep_on_disk && p->pack_keep) ||
> - (ignore_packed_keep_in_core && p->pack_keep_in_core)))
> - return 0;
>
> /* we don't know yet; keep looking for more packs */
> return -1;
I know I wrote this patch, but just looking it over again with a
critical eye: it looks like more re-ordering could avoid work in some
cases.
In particular, has_object_kept_pack() is a potentially expensive call.
But if "(local && !p->pack_local)" is true, then we could cheaply exit
the function with "0", regardless of what the keep requirement says.
That's not a case that I think anybody cares that deeply about (and it
certainly is not covered by t/perf). But I think it does regress in this
patch. Prior to the patch, we'd check that condition before returning
-1, and it was the caller who would then continue to search through all
the kept packs. Now we do it preemptively.
I think just bumping that:
if (local && !p->pack_local)
return 0;
above the new code would fix it. Or to lay out the logic more fully, the
order of checks should be:
- does _this_ pack we found the object in disqualify it. If so, we can
cheaply return 0. And that applies to both keep and local rules.
- otherwise, check all packs via has_object_kept_pack(), which is
cheaper than continuing to iterate through all packs by returning
-1.
- once we know definitively about keep-packs, then check any shortcuts
related to local packs (like !have_non_local_packs)
- and then if no shortcuts, we return -1
I think that might be easier to express by rewriting the patch. :)
-Peff
next prev parent reply other threads:[~2021-02-17 16:06 UTC|newest]
Thread overview: 120+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-19 23:23 [PATCH 00/10] repack: support repacking into a geometric sequence Taylor Blau
2021-01-19 23:24 ` [PATCH 01/10] packfile: introduce 'find_kept_pack_entry()' Taylor Blau
2021-01-20 13:40 ` Derrick Stolee
2021-01-20 14:38 ` Taylor Blau
2021-01-29 2:33 ` Junio C Hamano
2021-01-29 18:38 ` Taylor Blau
2021-01-29 19:31 ` Jeff King
2021-01-29 20:20 ` Junio C Hamano
2021-01-19 23:24 ` [PATCH 02/10] revision: learn '--no-kept-objects' Taylor Blau
2021-01-29 3:10 ` Junio C Hamano
2021-01-29 19:13 ` Taylor Blau
2021-01-19 23:24 ` [PATCH 03/10] builtin/pack-objects.c: learn '--assume-kept-packs-closed' Taylor Blau
2021-01-29 3:21 ` Junio C Hamano
2021-01-29 19:19 ` Jeff King
2021-01-29 20:01 ` Taylor Blau
2021-01-29 20:25 ` Jeff King
2021-01-29 22:10 ` Taylor Blau
2021-01-29 22:57 ` Jeff King
2021-01-29 23:03 ` Junio C Hamano
2021-01-29 23:28 ` Taylor Blau
2021-02-02 3:04 ` Taylor Blau
2021-01-29 23:31 ` Jeff King
2021-01-29 22:13 ` Junio C Hamano
2021-01-29 20:30 ` Junio C Hamano
2021-01-29 22:43 ` Jeff King
2021-01-29 22:53 ` Taylor Blau
2021-01-29 23:00 ` Jeff King
2021-01-29 23:10 ` Junio C Hamano
2021-01-19 23:24 ` [PATCH 04/10] p5303: add missing &&-chains Taylor Blau
2021-01-19 23:24 ` [PATCH 05/10] p5303: measure time to repack with keep Taylor Blau
2021-01-29 3:40 ` Junio C Hamano
2021-01-29 19:32 ` Jeff King
2021-01-29 20:04 ` [PATCH] p5303: avoid sed GNU-ism Jeff King
2021-01-29 20:19 ` Eric Sunshine
2021-01-29 20:27 ` Jeff King
2021-01-29 20:36 ` Eric Sunshine
2021-01-29 22:11 ` Taylor Blau
2021-01-29 20:38 ` [PATCH 05/10] p5303: measure time to repack with keep Junio C Hamano
2021-01-29 22:10 ` Jeff King
2021-01-29 23:12 ` Junio C Hamano
2021-01-19 23:24 ` [PATCH 06/10] pack-objects: rewrite honor-pack-keep logic Taylor Blau
2021-01-19 23:24 ` [PATCH 07/10] packfile: add kept-pack cache for find_kept_pack_entry() Taylor Blau
2021-01-19 23:24 ` [PATCH 08/10] builtin/pack-objects.c: teach '--keep-pack-stdin' Taylor Blau
2021-01-19 23:24 ` [PATCH 09/10] builtin/repack.c: extract loose object handling Taylor Blau
2021-01-20 13:59 ` Derrick Stolee
2021-01-20 14:34 ` Taylor Blau
2021-01-20 15:51 ` Derrick Stolee
2021-01-21 3:45 ` Junio C Hamano
2021-01-19 23:24 ` [PATCH 10/10] builtin/repack.c: add '--geometric' option Taylor Blau
2021-01-20 14:05 ` [PATCH 00/10] repack: support repacking into a geometric sequence Derrick Stolee
2021-02-04 3:58 ` [PATCH v2 0/8] " Taylor Blau
2021-02-04 3:58 ` [PATCH v2 1/8] packfile: introduce 'find_kept_pack_entry()' Taylor Blau
2021-02-16 21:42 ` Jeff King
2021-02-16 21:48 ` Taylor Blau
2021-02-04 3:58 ` [PATCH v2 2/8] revision: learn '--no-kept-objects' Taylor Blau
2021-02-16 23:17 ` Jeff King
2021-02-17 18:35 ` Taylor Blau
2021-02-04 3:59 ` [PATCH v2 3/8] builtin/pack-objects.c: add '--stdin-packs' option Taylor Blau
2021-02-16 23:46 ` Jeff King
2021-02-17 18:59 ` Taylor Blau
2021-02-17 19:21 ` Jeff King
2021-02-04 3:59 ` [PATCH v2 4/8] p5303: add missing &&-chains Taylor Blau
2021-02-04 3:59 ` [PATCH v2 5/8] p5303: measure time to repack with keep Taylor Blau
2021-02-16 23:58 ` Jeff King
2021-02-17 0:02 ` Jeff King
2021-02-17 19:13 ` Taylor Blau
2021-02-17 19:25 ` Jeff King
2021-02-04 3:59 ` [PATCH v2 6/8] builtin/pack-objects.c: rewrite honor-pack-keep logic Taylor Blau
2021-02-17 16:05 ` Jeff King [this message]
2021-02-17 19:23 ` Taylor Blau
2021-02-17 19:29 ` Jeff King
2021-02-04 3:59 ` [PATCH v2 7/8] packfile: add kept-pack cache for find_kept_pack_entry() Taylor Blau
2021-02-17 17:11 ` Jeff King
2021-02-17 19:54 ` Taylor Blau
2021-02-17 20:25 ` Jeff King
2021-02-17 20:29 ` Taylor Blau
2021-02-17 21:43 ` Jeff King
2021-02-04 3:59 ` [PATCH v2 8/8] builtin/repack.c: add '--geometric' option Taylor Blau
2021-02-17 18:17 ` Jeff King
2021-02-17 20:01 ` Taylor Blau
2021-02-17 0:01 ` [PATCH v2 0/8] repack: support repacking into a geometric sequence Jeff King
2021-02-17 18:18 ` Jeff King
2021-02-18 3:14 ` [PATCH v3 " Taylor Blau
2021-02-18 3:14 ` [PATCH v3 1/8] packfile: introduce 'find_kept_pack_entry()' Taylor Blau
2021-02-18 3:14 ` [PATCH v3 2/8] revision: learn '--no-kept-objects' Taylor Blau
2021-02-18 3:14 ` [PATCH v3 3/8] builtin/pack-objects.c: add '--stdin-packs' option Taylor Blau
2021-02-18 3:14 ` [PATCH v3 4/8] p5303: add missing &&-chains Taylor Blau
2021-02-18 3:14 ` [PATCH v3 5/8] p5303: measure time to repack with keep Taylor Blau
2021-02-18 3:14 ` [PATCH v3 6/8] builtin/pack-objects.c: rewrite honor-pack-keep logic Taylor Blau
2021-02-18 3:14 ` [PATCH v3 7/8] packfile: add kept-pack cache for find_kept_pack_entry() Taylor Blau
2021-02-18 3:14 ` [PATCH v3 8/8] builtin/repack.c: add '--geometric' option Taylor Blau
2021-02-23 0:31 ` [PATCH v3 0/8] repack: support repacking into a geometric sequence Jeff King
2021-02-23 1:06 ` Taylor Blau
2021-02-23 1:42 ` Jeff King
2021-02-23 2:24 ` [PATCH v4 " Taylor Blau
2021-02-23 2:25 ` [PATCH v4 1/8] packfile: introduce 'find_kept_pack_entry()' Taylor Blau
2021-02-23 2:25 ` [PATCH v4 2/8] revision: learn '--no-kept-objects' Taylor Blau
2021-02-23 2:25 ` [PATCH v4 3/8] builtin/pack-objects.c: add '--stdin-packs' option Taylor Blau
2021-02-23 8:07 ` Junio C Hamano
2021-02-23 18:51 ` Jeff King
2021-02-23 2:25 ` [PATCH v4 4/8] p5303: add missing &&-chains Taylor Blau
2021-02-23 2:25 ` [PATCH v4 5/8] p5303: measure time to repack with keep Taylor Blau
2021-02-23 2:25 ` [PATCH v4 6/8] builtin/pack-objects.c: rewrite honor-pack-keep logic Taylor Blau
2021-02-23 2:25 ` [PATCH v4 7/8] packfile: add kept-pack cache for find_kept_pack_entry() Taylor Blau
2021-02-23 2:25 ` [PATCH v4 8/8] builtin/repack.c: add '--geometric' option Taylor Blau
2021-02-24 23:19 ` Junio C Hamano
2021-02-24 23:43 ` Junio C Hamano
2021-03-04 21:40 ` Taylor Blau
2021-03-04 21:55 ` Taylor Blau
2021-02-23 3:39 ` [PATCH v4 0/8] repack: support repacking into a geometric sequence Jeff King
2021-02-23 7:43 ` Junio C Hamano
2021-02-23 18:44 ` Jeff King
2021-02-23 19:54 ` Martin Fick
2021-02-23 20:06 ` Taylor Blau
2021-02-23 21:57 ` Martin Fick
2021-02-23 20:15 ` Jeff King
2021-02-23 21:41 ` Martin Fick
2021-02-23 21:53 ` Jeff King
2021-02-24 18:13 ` Martin Fick
2021-02-26 6:23 ` Jeff King
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