From: Pierre Neidhardt <mail@ambrevar.xyz>
To: "Ludovic Courtès" <ludo@gnu.org>
Cc: guix-devel <guix-devel@gnu.org>,
"Nicolò Balzarotti" <anothersms@gmail.com>
Subject: Re: When substitute download + decompression is CPU-bound
Date: Tue, 15 Dec 2020 13:31:23 +0100 [thread overview]
Message-ID: <87sg879rok.fsf@ambrevar.xyz> (raw)
In-Reply-To: <87blevmh2l.fsf@gnu.org>
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Hi Ludo,
Ludovic Courtès <ludo@gnu.org> writes:
> Well, ‘guix publish’ would first need to create multi-member archives,
> right?
Correct, but it's trivial once the bindings have been implemented.
> Also, lzlib (which is what we use) does not implement parallel
> decompression, AIUI.
Yes it does, multi-member archives is a non-optional part of the Lzip
specs, and lzlib implemetns all the specs.
> Even if it did, would we be able to take advantage of it? Currently
> ‘restore-file’ expects to read an archive stream sequentially.
Yes it works, I just tried this:
--8<---------------cut here---------------start------------->8---
cat big-file.lz | plzip -d -o big-file -
--8<---------------cut here---------------end--------------->8---
Decompression happens in parallel.
> Even if I’m wrong :-), decompression speed would at best be doubled on
> multi-core machines (wouldn’t help much on low-end ARM devices), and
> that’s very little compared to the decompression speed achieved by zstd.
Why doubled? If the archive has more than CORE-NUMBER segments, then
the decompression duration can be divided by CORE-NUMBER.
All that said, I think we should have both:
- Parallel lzip support is the easiest to add at this point.
It's the best option for people with low bandwidth. This can benefit
most of the planet I suppose.
- zstd is best for users with high bandwidth (or with slow hardware).
We need to write the necessary bindings though, so it will take a bit
more time.
Then the users can choose which compression they prefer, mostly
depending on their hardware and bandwidth.
--
Pierre Neidhardt
https://ambrevar.xyz/
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next prev parent reply other threads:[~2020-12-15 12:39 UTC|newest]
Thread overview: 43+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-14 22:20 When substitute download + decompression is CPU-bound Ludovic Courtès
2020-12-14 22:29 ` Julien Lepiller
2020-12-14 22:59 ` Nicolò Balzarotti
2020-12-15 7:52 ` Pierre Neidhardt
2020-12-15 9:45 ` Nicolò Balzarotti
2020-12-15 9:54 ` Pierre Neidhardt
2020-12-15 10:03 ` Nicolò Balzarotti
2020-12-15 10:13 ` Pierre Neidhardt
2020-12-15 10:14 ` Pierre Neidhardt
2020-12-15 11:42 ` Ludovic Courtès
2020-12-15 12:31 ` Pierre Neidhardt [this message]
2020-12-18 14:59 ` Ludovic Courtès
2020-12-18 15:33 ` Pierre Neidhardt
2020-12-15 11:36 ` Ludovic Courtès
2020-12-15 11:45 ` Nicolò Balzarotti
2020-12-15 10:40 ` Jonathan Brielmaier
2020-12-15 19:43 ` Joshua Branson
2021-01-07 10:45 ` Guillaume Le Vaillant
2021-01-07 11:00 ` Pierre Neidhardt
2021-01-07 11:33 ` Guillaume Le Vaillant
2021-01-14 21:51 ` Ludovic Courtès
2021-01-14 22:08 ` Nicolò Balzarotti
2021-01-28 17:53 ` Are gzip-compressed substitutes still used? Ludovic Courtès
2021-03-17 17:12 ` Ludovic Courtès
2021-03-17 17:33 ` Léo Le Bouter
2021-03-17 18:08 ` Vagrant Cascadian
2021-03-18 0:03 ` zimoun
2021-03-18 16:00 ` Vagrant Cascadian
2021-03-18 18:53 ` Leo Famulari
2021-03-20 11:23 ` Ludovic Courtès
2021-03-17 18:06 ` zimoun
2021-03-17 18:20 ` Jonathan Brielmaier
2021-03-18 17:25 ` Pierre Neidhardt
2021-01-15 8:10 ` When substitute download + decompression is CPU-bound Pierre Neidhardt
2021-01-28 17:58 ` Ludovic Courtès
2021-01-29 9:45 ` Pierre Neidhardt
2021-01-29 11:23 ` Guillaume Le Vaillant
2021-01-29 11:55 ` Nicolò Balzarotti
2021-01-29 12:13 ` Pierre Neidhardt
2021-01-29 13:06 ` Guillaume Le Vaillant
2021-01-29 14:55 ` Nicolò Balzarotti
2021-02-01 22:18 ` Ludovic Courtès
2021-01-29 13:33 ` zimoun
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