[PATCH 6 of 8 "] compression: introduce an official `format.revlog-compression` option

Josef 'Jeff' Sipek jeffpc at josefsipek.net
Tue Apr 2 03:42:56 EDT 2019


On Sun, Mar 31, 2019 at 17:36:22 +0200, Pierre-Yves David wrote:
...
> compression: introduce an official `format.revlog-compression` option
> 
> This option superseed the `experiment.format.compression` option. The value

s/superseed/supersedes/ :)

> currently supported are zlib (default) and zstd (if Mercurial was compiled with
> zstd support).
> 
> The option gained an explicite reference to `revlog` since this is the target

s/explicite/explicit/

> usage here. Different storage methods might requires different compression
> strategies.

s/requires/require/

> 
> In our tests, using zstd give a significant CPU usage improvement (both
> compression and decompressing) while keeping similar repository size.
> 
> Zstd as other interresting mode (dictionnaly, pre-text, etc…) that are probably

I'm guessing here: s/dictionnaly/dictionary/ ?

> worth exploring. However, just play switching from zlib to zstd provide a large
> benefit.

s/play/plain/

...
> diff --git a/mercurial/help/config.txt b/mercurial/help/config.txt
> --- a/mercurial/help/config.txt
> +++ b/mercurial/help/config.txt
> @@ -866,6 +866,13 @@ https://www.mercurial-scm.org/wiki/Missi
>      Repositories with this on-disk format require Mercurial version 4.7
>  
>      Enabled by default.
> +``revlog-compression``
> +    Compression algorithm used by revlog. Supported value are `zlib` and `zstd`.
> +    The `zlib` engine is the historical default of Mercurial. `zstd` is a newer
> +    format that is usually a net win over `zlib` operating faster at better
> +    compression rate. Use `zstd` to reduce CPU usage.
> +
> +    On some system, Mercurial installation may lack `zstd` supports. Default is `zlib`.

This says that 'zlib' is the default - twice.  Should it repeat itself like
this?

Jeff.

-- 
Don't drink and derive. Alcohol and algebra don't mix.


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