Re: [PATCH 0/9] Prefix-compress on-disk index entries

> 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%.