From: Nguyen Thai Ngoc Duy <pclouds@gmail.com>
To: Junio C Hamano <gitster@pobox.com>
Cc: git@vger.kernel.org
Subject: Re: [PATCH 0/9] Prefix-compress on-disk index entries
Date: Wed, 4 Apr 2012 19:34:20 +0700 [thread overview]
Message-ID: <CACsJy8A+cJtzKdqJSWbmjT1LgP10LB69-NHfOv8S6BusGcMeFw@mail.gmail.com> (raw)
In-Reply-To: <1333493596-14202-1-git-send-email-gitster@pobox.com>
On Wed, Apr 4, 2012 at 5:53 AM, Junio C Hamano <gitster@pobox.com> wrote:
> This is still rough,
but nice cleanups
> but with this patch I am getting:
>
> $ ls -l .git/index*
> -rw-r----- 1 jch eng 25586488 2012-04-03 15:27 .git/index
> -rw-r----- 1 jch eng 14654328 2012-04-03 15:38 .git/index-4
>
> in a clone of WebKit repository that has 183175 paths.
>
> With hot-cache with no local modification:
>
> $ time sh -c 'GIT_INDEX_FILE=.git/index-4 git diff'
> real 0m0.469s
> user 0m0.130s
> sys 0m0.330s
>
> $ time sh -c 'git diff'
> real 0m0.677s
> user 0m0.290s
> sys 0m0.370s
I wonder what causes user time drop from .29s to .13s here. I think
the main patch should increase computation, even only slightly, not
less. Or is it noise?
> The updated format is not documented yet, as I didn't intend (and I still
> am not committed) to declare a change along this line the official "v4"
> format; I was merely being curious to see how much improvements we can get
> from a trivial approach like this.
Anything else you have in mind for v4? Any chance we can adopt crc32
instead of sha-1? We could divide the index into many smaller parts
for checksum, for example one crc32 every 100 entries, and one (or
sha-1) for each extension. It should not complicate the code too much.
--
Duy
next prev parent reply other threads:[~2012-04-04 12:34 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-04-03 22:53 [PATCH 0/9] Prefix-compress on-disk index entries Junio C Hamano
2012-04-03 22:53 ` [PATCH 1/9] varint: make it available outside the context of pack Junio C Hamano
2012-04-03 22:53 ` [PATCH 2/9] cache.h: hide on-disk index details Junio C Hamano
2012-04-03 22:53 ` [PATCH 3/9] read-cache.c: allow unaligned mapping of the index file Junio C Hamano
2012-04-03 22:53 ` [PATCH 4/9] read-cache.c: make create_from_disk() report number of bytes it consumed Junio C Hamano
2012-04-03 22:53 ` [PATCH 5/9] read-cache.c: report the header version we do not understand Junio C Hamano
2012-04-03 22:53 ` [PATCH 6/9] read-cache.c: move code to copy ondisk to incore cache to a helper function Junio C Hamano
2012-04-03 22:53 ` [PATCH 7/9] read-cache.c: move code to copy incore to ondisk " Junio C Hamano
2012-04-03 22:53 ` [PATCH 8/9] read-cache.c: read prefix-compressed names in index on-disk version v4 Junio C Hamano
2012-04-03 22:53 ` [PATCH 9/9] read-cache.c: write index v4 format Junio C Hamano
2012-04-04 1:44 ` [PATCH 0/9] Prefix-compress on-disk index entries David Barr
2012-04-04 15:33 ` Junio C Hamano
2012-04-04 16:57 ` Junio C Hamano
2012-04-04 16:58 ` [PATCH 2/2] update-index: upgrade/downgrade on-disk index version Junio C Hamano
2012-04-04 12:34 ` Nguyen Thai Ngoc Duy [this message]
2012-04-04 18:44 ` [PATCH 0/9] Prefix-compress on-disk index entries Junio C Hamano
2012-04-06 8:41 ` David Barr
2012-05-02 1:58 ` Nguyen Thai Ngoc Duy
2012-05-02 4:26 ` David Barr
2012-04-27 22:58 ` [PATCH 1/2] unpack-trees: preserve the index file version of original Junio C Hamano
2012-04-27 23:02 ` [PATCH 2/2] index-v4: document the entry format Junio C Hamano
2012-04-30 17:20 ` Thomas Rast
2012-05-01 4:00 ` Junio C Hamano
2012-05-01 21:43 ` Thomas Rast
2012-05-02 15:12 ` Shawn Pearce
2012-05-02 17:04 ` Junio C Hamano
2012-05-02 17:13 ` Shawn Pearce
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