From: Nguyen Thai Ngoc Duy <pclouds@gmail.com>
Date: Wed, 02 May 2012 01:58:50 GMT
Subject: Re: [PATCH 0/9] Prefix-compress on-disk index entries
Message-ID: <CACsJy8DZ4t0f_mdDJTUZvz_pBPrPTsEBxHEkYREowWm6D1ikkw@mail.gmail.com>
In-Reply-To: <CAFfmPPNHkK3SB8cGjfJiVoQoSg2OLL8B5--mwH8HShhJ1WGy2g@mail.gmail.com>

On Fri, Apr 6, 2012 at 3:41 PM, David Barr <davidbarr@google.com> wrote:
> On Thu, Apr 5, 2012 at 4:44 AM, Junio C Hamano <gitster@pobox.com> wrote:
>> 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.
>
> I hacked together a quick patch to try predictive coding the other
> fields of the index. I got a further 34% improvement in size over
> this series. Patches to come. I just used the previous cache entry as
> the predictor and reused varint.h together with zigzag encoding[1].
>
> That's a total improvement in size over v2 of 62%.

Have you posted (and I missed) the patches? I'm interested in seeing
what changes you made.

> [1] https://developers.google.com/protocol-buffers/docs/encoding#types
-- 
Duy