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From: Ben Peart <peartben@gmail.com>
To: Duy Nguyen <pclouds@gmail.com>
Cc: Jeff King <peff@peff.net>, Ben Peart <Ben.Peart@microsoft.com>,
	Git Mailing List <git@vger.kernel.org>,
	Junio C Hamano <gitster@pobox.com>
Subject: Re: [PATCH v1 0/3] [RFC] Speeding up checkout (and merge, rebase, etc)
Date: Mon, 23 Jul 2018 16:51:38 -0400	[thread overview]
Message-ID: <6ff6fbdc-d9cf-019f-317c-7fdba31105c6@gmail.com> (raw)
In-Reply-To: <CACsJy8D-3sSnoyQZKxeLK-2RmpJSGkziAp5Gf4QpUnxwnhchSQ@mail.gmail.com>



On 7/23/2018 1:03 PM, Duy Nguyen wrote:
> On Mon, Jul 23, 2018 at 5:50 PM Ben Peart <peartben@gmail.com> wrote:
>>> Anyway, on to the actual discussion:
>>>
>>>> Here is a checkout command with tracing turned on to demonstrate where the
>>>> time is spent.  Note, this is somewhat of a �best case� as I�m simply
>>>> checking out the current commit:
>>>>
>>>> benpeart@gvfs-perf MINGW64 /f/os/src (official/rs_es_debug_dev)
>>>> $ /usr/src/git/git.exe checkout
>>>> 12:31:50.419016 read-cache.c:2006       performance: 1.180966800 s: read cache .git/index
>>>> 12:31:51.184636 name-hash.c:605         performance: 0.664575200 s: initialize name hash
>>>> 12:31:51.200280 preload-index.c:111     performance: 0.019811600 s: preload index
>>>> 12:31:51.294012 read-cache.c:1543       performance: 0.094515600 s: refresh index
>>>> 12:32:29.731344 unpack-trees.c:1358     performance: 33.889840200 s: traverse_trees
>>>> 12:32:37.512555 read-cache.c:2541       performance: 1.564438300 s: write index, changed mask = 28
>>>> 12:32:44.918730 unpack-trees.c:1358     performance: 7.243155600 s: traverse_trees
>>>> 12:32:44.965611 diff-lib.c:527          performance: 7.374729200 s: diff-index
>>>> Waiting for GVFS to parse index and update placeholder files...Succeeded
>>>> 12:32:46.824986 trace.c:420             performance: 57.715656000 s: git command: 'C:\git-sdk-64\usr\src\git\git.exe' checkout
>>>
>>> What's the current state of the index before this checkout?
>>
>> This was after running "git checkout" multiple times so there was really
>> nothing for git to do.
> 
> Hmm.. this means cache-tree is fully valid, unless you have changes in
> index. We're quite aggressive in repairing cache-tree since aecf567cbf
> (cache-tree: create/update cache-tree on checkout - 2014-07-05). If we
> have very good cache-tree records and still spend 33s on
> traverse_trees, maybe there's something else.
> 

I'm not at all familiar with the cache-tree and couldn't find any 
documentation on it other than index-format.txt which says "it helps 
speed up tree object generation for a new commit."  In this particular 
case, no new commit is being created so I don't know that the cache-tree 
would help.

After a quick look at the code, the only place I can find that tries to 
use cache_tree_matches_traversal() is in unpack_callback() and that only 
happens if n == 1 and in the "git checkout" case, n == 2. Am I missing 
something?

  reply	other threads:[~2018-07-23 20:51 UTC|newest]

Thread overview: 121+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-07-18 20:45 [PATCH v1 0/3] [RFC] Speeding up checkout (and merge, rebase, etc) Ben Peart
2018-07-18 20:45 ` [PATCH v1 1/3] add unbounded Multi-Producer-Multi-Consumer queue Ben Peart
2018-07-18 20:57   ` Stefan Beller
2018-07-19 19:11   ` Junio C Hamano
2018-07-18 20:45 ` [PATCH v1 2/3] add performance tracing around traverse_trees() in unpack_trees() Ben Peart
2018-07-18 20:45 ` [PATCH v1 3/3] Add initial parallel version of unpack_trees() Ben Peart
2018-07-18 22:56   ` Junio C Hamano
2018-07-18 21:02 ` [PATCH v1 0/3] [RFC] Speeding up checkout (and merge, rebase, etc) Stefan Beller
2018-07-18 21:34 ` Jeff King
2018-07-23 15:48   ` Ben Peart
2018-07-23 17:03     ` Duy Nguyen
2018-07-23 20:51       ` Ben Peart [this message]
2018-07-24  4:20         ` Jeff King
2018-07-24 15:33           ` Duy Nguyen
2018-07-25 20:56             ` Ben Peart
2018-07-26  5:30               ` Duy Nguyen
2018-07-26 16:30                 ` Duy Nguyen
2018-07-26 19:40                   ` Junio C Hamano
2018-07-27 15:42                     ` Duy Nguyen
2018-07-27 16:22                       ` Ben Peart
2018-07-27 18:00                         ` Duy Nguyen
2018-07-27 17:14                       ` Junio C Hamano
2018-07-27 17:52                         ` Duy Nguyen
2018-07-29  6:24                           ` Duy Nguyen
2018-07-29 10:33                       ` [PATCH v2 0/4] Speed up unpack_trees() Nguyễn Thái Ngọc Duy
2018-07-29 10:33                         ` [PATCH v2 1/4] unpack-trees.c: add performance tracing Nguyễn Thái Ngọc Duy
2018-07-30 20:16                           ` Ben Peart
2018-07-29 10:33                         ` [PATCH v2 2/4] unpack-trees: optimize walking same trees with cache-tree Nguyễn Thái Ngọc Duy
2018-07-30 20:52                           ` Ben Peart
2018-07-29 10:33                         ` [PATCH v2 3/4] unpack-trees: reduce malloc in cache-tree walk Nguyễn Thái Ngọc Duy
2018-07-30 20:58                           ` Ben Peart
2018-07-29 10:33                         ` [PATCH v2 4/4] unpack-trees: cheaper index update when walking by cache-tree Nguyễn Thái Ngọc Duy
2018-08-08 18:46                           ` Elijah Newren
2018-08-10 16:39                             ` Duy Nguyen
2018-08-10 18:39                               ` Elijah Newren
2018-08-10 19:30                                 ` Duy Nguyen
2018-08-10 19:40                                   ` Elijah Newren
2018-08-10 19:48                                     ` Duy Nguyen
2018-07-30 18:10                         ` [PATCH v2 0/4] Speed up unpack_trees() Ben Peart
2018-07-31 15:31                           ` Duy Nguyen
2018-07-31 16:50                             ` Ben Peart
2018-07-31 17:31                               ` Ben Peart
2018-08-01 16:38                                 ` Duy Nguyen
2018-08-08 20:53                                   ` Ben Peart
2018-08-09  8:16                                     ` Ben Peart
2018-08-10 16:08                                       ` Duy Nguyen
2018-08-10 15:51                                     ` Duy Nguyen
2018-07-30 21:04                         ` Ben Peart
2018-08-04  5:37                         ` [PATCH v3 " Nguyễn Thái Ngọc Duy
2018-08-04  5:37                           ` [PATCH v3 1/4] unpack-trees: add performance tracing Nguyễn Thái Ngọc Duy
2018-08-04  5:37                           ` [PATCH v3 2/4] unpack-trees: optimize walking same trees with cache-tree Nguyễn Thái Ngọc Duy
2018-08-08 18:23                             ` Elijah Newren
2018-08-10 16:29                               ` Duy Nguyen
2018-08-10 18:48                                 ` Elijah Newren
2018-08-04  5:37                           ` [PATCH v3 3/4] unpack-trees: reduce malloc in cache-tree walk Nguyễn Thái Ngọc Duy
2018-08-08 18:30                             ` Elijah Newren
2018-08-04  5:37                           ` [PATCH v3 4/4] unpack-trees: cheaper index update when walking by cache-tree Nguyễn Thái Ngọc Duy
2018-08-06 15:48                           ` [PATCH v3 0/4] Speed up unpack_trees() Junio C Hamano
2018-08-06 15:59                             ` Duy Nguyen
2018-08-06 18:59                               ` Junio C Hamano
2018-08-08 17:00                                 ` Ben Peart
2018-08-08 17:46                               ` Junio C Hamano
2018-08-08 18:12                                 ` Junio C Hamano
2018-08-08 18:39                                   ` Junio C Hamano
2018-08-10 16:53                                     ` Duy Nguyen
2018-08-12  8:15                           ` [PATCH v4 0/5] " Nguyễn Thái Ngọc Duy
2018-08-12  8:15                             ` [PATCH v4 1/5] trace.h: support nested performance tracing Nguyễn Thái Ngọc Duy
2018-08-13 18:39                               ` Ben Peart
2018-08-12  8:15                             ` [PATCH v4 2/5] unpack-trees: add " Nguyễn Thái Ngọc Duy
2018-08-12 10:05                               ` Thomas Adam
2018-08-13 18:50                                 ` Junio C Hamano
2018-08-13 18:44                               ` Ben Peart
2018-08-13 19:25                               ` Jeff King
2018-08-13 19:36                                 ` Stefan Beller
2018-08-13 20:11                                   ` Ben Peart
2018-08-13 19:52                                 ` Duy Nguyen
2018-08-13 21:47                                   ` Jeff King
2018-08-13 22:41                                 ` Junio C Hamano
2018-08-14 18:19                                   ` Jeff Hostetler
2018-08-14 18:32                                     ` Duy Nguyen
2018-08-14 18:44                                       ` Stefan Beller
2018-08-14 18:51                                         ` Duy Nguyen
2018-08-14 19:54                                           ` Jeff King
2018-08-14 20:52                                           ` Junio C Hamano
2018-08-15 16:32                                             ` Duy Nguyen
2018-08-15 18:28                                               ` Junio C Hamano
2018-08-14 20:14                                         ` Jeff Hostetler
2018-08-12  8:15                             ` [PATCH v4 3/5] unpack-trees: optimize walking same trees with cache-tree Nguyễn Thái Ngọc Duy
2018-08-13 18:58                               ` Ben Peart
2018-08-15 16:38                                 ` Duy Nguyen
2018-08-12  8:15                             ` [PATCH v4 4/5] unpack-trees: reduce malloc in cache-tree walk Nguyễn Thái Ngọc Duy
2018-08-12  8:15                             ` [PATCH v4 5/5] unpack-trees: reuse (still valid) cache-tree from src_index Nguyễn Thái Ngọc Duy
2018-08-13 15:48                               ` Elijah Newren
2018-08-13 15:57                                 ` Duy Nguyen
2018-08-13 16:05                                 ` Ben Peart
2018-08-13 16:25                                   ` Duy Nguyen
2018-08-13 17:15                                     ` Ben Peart
2018-08-13 19:01                             ` [PATCH v4 0/5] Speed up unpack_trees() Junio C Hamano
2018-08-14 19:19                             ` Ben Peart
2018-08-18 14:41                             ` [PATCH v5 0/7] " Nguyễn Thái Ngọc Duy
2018-08-18 14:41                               ` [PATCH v5 1/7] trace.h: support nested performance tracing Nguyễn Thái Ngọc Duy
2018-08-18 14:41                               ` [PATCH v5 2/7] unpack-trees: add " Nguyễn Thái Ngọc Duy
2018-08-18 14:41                               ` [PATCH v5 3/7] unpack-trees: optimize walking same trees with cache-tree Nguyễn Thái Ngọc Duy
2018-08-20 12:43                                 ` Ben Peart
2018-08-18 14:41                               ` [PATCH v5 4/7] unpack-trees: reduce malloc in cache-tree walk Nguyễn Thái Ngọc Duy
2018-08-18 14:41                               ` [PATCH v5 5/7] unpack-trees: reuse (still valid) cache-tree from src_index Nguyễn Thái Ngọc Duy
2018-08-18 14:41                               ` [PATCH v5 6/7] unpack-trees: add missing cache invalidation Nguyễn Thái Ngọc Duy
2018-08-18 14:41                               ` [PATCH v5 7/7] cache-tree: verify valid cache-tree in the test suite Nguyễn Thái Ngọc Duy
2018-08-18 21:45                                 ` Elijah Newren
2018-08-18 22:01                               ` [PATCH v5 0/7] Speed up unpack_trees() Elijah Newren
2018-08-19  5:09                                 ` Duy Nguyen
2018-08-25 12:18                               ` [PATCH] Document update for nd/unpack-trees-with-cache-tree Nguyễn Thái Ngọc Duy
2018-08-25 12:31                                 ` Martin Ågren
2018-08-25 13:02                                 ` [PATCH v2] " Nguyễn Thái Ngọc Duy
2018-07-27 15:50                     ` [PATCH v1 0/3] [RFC] Speeding up checkout (and merge, rebase, etc) Ben Peart
2018-07-26 16:35               ` Duy Nguyen
2018-07-24  5:54         ` Junio C Hamano
2018-07-24 15:13         ` Duy Nguyen
2018-07-24 21:21           ` Jeff King
2018-07-25 16:09           ` Ben Peart
2018-07-24  4:27       ` Jeff King

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