On Fri, Jul 10, 2020 at 12:59:37AM -0600, Chris Murphy wrote:
> https://paste.centos.org/view/f4165396
>
> Two workloads: install and update. It might seem like an update is
> both read and write dependent, but the rpms are already compressed and
> don't get compressed again. The differences, I expect, are mostly
> write performance. And this suggests it's a wash. I'd say this setup
> is fairly middle of the pack.
>
> The space savings, however, isn't a wash.
And if I'm reading it right, a significant win for either btrfs setup over
ext4.
Space wise or the update time? I think the install times are moderated by the installer image being tightly bound by xz decompression. The same happens to zstd compressed RPM for updates, to a lesser degree, and it might be better threaded, so we see a bigger difference.
There is also noise contributed by the fact it's done in a VM, and using sparse files. That could have disproportionately penalized ext4. But as a sanity test that there isn't anything particular screwy going on performance wise, it's probably fine.
For example, the kernel load times. Why is the compressed btrfs one so much faster? Twice. Weird. All three setups, the kernel is on ext4. All six should be the same. So there is error.
--
Chris Murphy