On Wed, Jul 08, 2020 at 11:37:11AM -0600, Chris Murphy wrote:
If it's the center, I think that favors the mount option approach
and
do it with the lowest level of compression, i.e. zstd:1. But this
suggests more benchmarking still, to make certain it's well understood
what the range of write performance hit could be in those scenarios.
Whereas the curated approach can just bypass most of that question -
the payload and workload for flatpak and usr and containers is fairly
fixed across all Fedora users rather than mixed content and workloads
found in ~/
I just did some quick tests out of curiousity. I tarred up /usr on my
system, resulting in a 9.8GB file. Ran this in my home dir on a
run-of-the-mill Western Digital SSD.
This results in:
compression file compression % better than
level size ratio previous
1 4.1G 41.36% -
2 3.8G 38.97% 6.1%
3 3.6G 36.81% 5.9%
4 3.6G 36.36% 1.2%
5 3.5G 35.63% 2.8%
6 3.5G 35.33% 2.0%
9 3.4G 34.19% -
19 2.8G 29.72% -
That's pretty good even at level 1. I don't think my setup is useful for
timing benchmarks, and also that takes more care than I want to put into it
this minute, but the interesting note is that levels 1-4 are all about the
same in speed (within 10 seconds) and level 5 suddenly 3x slower. I assume
that's not surprising to anyone who knows how zstd works. But also, unless
you go to crazy high levels, the gains above level 3 really drop off.
(19, by the way, is amazingly slow. Took almost an hour.)
--
Matthew Miller
<mattdm(a)fedoraproject.org>
Fedora Project Leader