From: Junio C Hamano <gitster@pobox.com>
To: Nguyen Thai Ngoc Duy <pclouds@gmail.com>
Cc: git@vger.kernel.org
Subject: Re: [PATCH 0/9] Prefix-compress on-disk index entries
Date: Wed, 04 Apr 2012 11:44:36 -0700 [thread overview]
Message-ID: <7vpqbn8hgr.fsf@alter.siamese.dyndns.org> (raw)
In-Reply-To: <CACsJy8A+cJtzKdqJSWbmjT1LgP10LB69-NHfOv8S6BusGcMeFw@mail.gmail.com> (Nguyen Thai Ngoc Duy's message of "Wed, 4 Apr 2012 19:34:20 +0700")
Nguyen Thai Ngoc Duy <pclouds@gmail.com> writes:
> On Wed, Apr 4, 2012 at 5:53 AM, Junio C Hamano <gitster@pobox.com> wrote:
> ...
> 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.
The main patch reduced the amount of the data needs to be sent to the
machinery to checksum and write to disk by about 45%, saving both I/O
and computation.
This is a tangent, but I wonder why we are not using csum-file API to do
this (I know the dircache code came first way before csum-file; I am
wondering why we haven't rewritten the codepath using it later).
> Anything else you have in mind for v4? Any chance we can adopt crc32
> instead of sha-1?
I am not interested in sacrificing integrity over unproven/unmeasured
performance "issues" on SHA-1, so I am not planning to experiment with
such a change myself. The choice of hashing algorithm from my point of
view is the least interesting part.
next prev parent reply other threads:[~2012-04-04 18:44 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 ` [PATCH 0/9] Prefix-compress on-disk index entries Nguyen Thai Ngoc Duy
2012-04-04 18:44 ` Junio C Hamano [this message]
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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