On Wed, Jul 8, 2020 at 1:45 PM Matthew Miller <mattdm(a)fedoraproject.org> wrote:
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.
Btrfs uses a cheap entropy estimator to decide if it should even try
to compress blocks. So it won't always do it. Hence results like this:
$ sudo compsize /usr
Processed 204133 files, 108496 regular extents (114715 refs), 101700 inline.
Type Perc Disk Usage Uncompressed Referenced
TOTAL 57% 3.2G 5.7G 6.2G
none 100% 1.8G 1.8G 1.9G
zstd 36% 1.3G 3.8G 4.3G
--
Chris Murphy