[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
> 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
> usage here. Different storage methods might requires different compression
> 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
> 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.
> + 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
Don't drink and derive. Alcohol and algebra don't mix.
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