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Re: Dired C idea
From: |
Michael Albinus |
Subject: |
Re: Dired C idea |
Date: |
Tue, 03 Aug 2021 13:43:14 +0200 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/28.0.50 (gnu/linux) |
Michael Albinus <michael.albinus@gmx.de> writes:
>> > Should be feasible. The hard part is a rule to determine, whether rsync
>> > is better suited than the existing implementation, with the given actual
>> > arguments. I suspect, that small directories and/or short files are
>> > better served with the current implementation.
>>
>> Do we really need to decide this? Wouldn't it be ok to use rsync
>> for all cases (where Tramp is not in use)?
>
> I would like to see some benchmark figures first. For example, I'm not
> sure that rsync performs better when the target directory does not exist
> yet, and there's nothing to sync.
I made some comparison between "cp -pr" and "rsync -pr" on shell
level. I've copied the whole Emacs tree to somewhere else. First the
case, that the target does not exist:
$ time cp -pr ~/src/emacs /tmp/emacs.cp
0.086u 1.322s 0:04.43 31.6% 0+0k 1817688+0io 1pf+0w
$ time rsync -pr ~/src/emacs /tmp/emacs.rsync
5.776u 2.069s 0:05.76 135.9% 0+0k 1384384+0io 1pf+0w
"rsync -pr" is slower than "cp -pr". Now I've applied the rsync command
again, to the unchanged directory tree with exisiting target:
$ time rsync -pr ~/src/emacs /tmp/emacs.rsync
6.116u 2.457s 0:06.63 129.1% 0+0k 1069632+0io 4pf+0w
It is even a little bit slower than the first rsync run. So I don't
know, whether there is really a performance boost when we use rsync for
local directory copies.
OTOH, `copy-directory' in files.el runs recursively `copy-file',
file-wise. Perhaps we could improve this implementation on C level.
Best regards, Michael.
- Re: Dired C idea, Michael Albinus, 2021/08/01
- Re: Dired C idea, Richard Stallman, 2021/08/01
- Re: Dired C idea, Arthur Miller, 2021/08/03
- Re: Dired C idea, Gregory Heytings, 2021/08/03
- Re: Dired C idea, Stefan Monnier, 2021/08/03
- Re: Dired C idea, Andreas Schwab, 2021/08/04
- Re: Dired C idea, Arthur Miller, 2021/08/04
- Re: Dired C idea, Fabrice Bauzac-Stehly, 2021/08/03