On compressing revlogs

Sune Foldager cryo at cyanite.org
Mon Jun 25 15:53:44 CDT 2012


On 2012-06-07 20:22, Martin Geisler wrote:
>"Bryan O'Sullivan" <bos at serpentine.com> writes:
>
>> On Thu, Jun 7, 2012 at 7:49 AM, Martin Geisler <mg at aragost.com> wrote:
>>
>> >   You should grab hold of Sune -- he worked on generaldelta and did some
>> >   earlier experiments with LZMA compression:
>> >
>> >    http://mercurial.markmail.org/thread/sqlsficnnwlbb7d2
>>
>> That's interesting, but not really appropriate to my situation - bzip2
>> and LZMA are hundreds of times too slow to be used for local revlog
>> storage. Even bzip2 or LZMA in the wire protocol makes a poor fit for
>> fast WANs, as they reduce bandwidth (abundant) at the cost of
>> increased CPU (scarce on the server).
>
>Ah, I see what you mean -- I guess Sune tried to optimize bandwidth at
>the cost of CPU.

Yes; I wanted to send as small bundles as possible. In my experience, lzma
is not that much slower ("hundreds"), but it does use a lot of memory.

-Sune


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