* Re: [gentoo-dev] Re: RFC: Hosting daily gx86 squashfs images and deltas
@ 2014-01-17 19:30 99% ` Michał Górny
0 siblings, 0 replies; 1+ results
From: Michał Górny @ 2014-01-17 19:30 UTC (permalink / raw
To: gentoo-dev; +Cc: 1i5t5.duncan
[-- Attachment #1: Type: text/plain, Size: 2119 bytes --]
Dnia 2014-01-17, o godz. 19:19:14
Duncan <1i5t5.duncan@cox.net> napisał(a):
> Michał Górny posted on Fri, 17 Jan 2014 17:27:30 +0100 as excerpted:
>
> > Now some numbers. I did some tests 'converting' late gx86 daily tarballs
> > to squashfs. I've used squashfs 4.2 with LZO compression since it's
> > quite good and very fast.
> >
> > 96M portage-20140108.sqfs
> [...]
> > 97M portage-20140114.sqfs
> > 97M portage-20140115.sqfs
> >
> > For deltas [...]
> >
> > 4,9M portage-20140108.sqfs-portage-20140109.sqfs.vcdiff.djw
> > 6,3M portage-20140109.sqfs-portage-20140110.sqfs.vcdiff.djw
> [...]
> > 8,5M portage-20140114.sqfs-portage-20140115.sqfs.vcdiff.djw
> >
> > As you can see, the deltas are quite large compared to the actual
> > changes. However, we could have expected that since we're diffing a
> > compressed filesystem. What's important, however, is that applying it
> > takes ~2.5 second on my 2 GHz Athlon64.
>
> And... eyeballing a 6 MiB average, diffs are ~1/16 the full squashfs
> size, perhaps a bit larger. So people updating once a week or even about
> every 10 days would see a bandwidth savings, provided the sync script was
> intelligent enough to apply updates serially.
>
> The breakover point would be roughly an update every two weeks, or twice
> a month, at which point just downloading a new full squashfs would be
> easier, at about the same bandwidth.
Yes, that's the initial goal. The update code would catch that
condition and perform full fetch instead.
However, it may be actually beneficial to provide other durations, like
weekly deltas. In my tests, the daily updates for this week summed up
to almost 50M while the weekly was barely 20M.
> > What do you think?
>
> How does this, particularly the metadata cache, interact with overlays?
> That's /my/ big question.
The same way as usual. Nothing special happens unless you override
eclasses via overlays. If you do that, you need unionfs to save
the cache updates -- but then, it has no point for you to use squashfs.
--
Best regards,
Michał Górny
[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 966 bytes --]
^ permalink raw reply [relevance 99%]
Results 1-1 of 1 | reverse | options above
-- pct% links below jump to the message on this page, permalinks otherwise --
2014-01-17 16:27 [gentoo-dev] RFC: Hosting daily gx86 squashfs images and deltas Michał Górny
2014-01-17 19:19 ` [gentoo-dev] " Duncan
2014-01-17 19:30 99% ` Michał Górny
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox