Bug#947759: Configuration optimizations for the cloud variant
On Tue, Feb 04, 2020 at 03:48:32PM -0800, Josh Triplett wrote:
> I would suggest testing on a c5.large. t2 and t3 have shared CPUs, so
> they have less consistent boot time. c5.large is about the same cost as
> t3.large, but will have far more consistent performance.
Performance definitely seems to vary quite a bit. Here are a few
samples from c5.large instances in us-west-2:
5.5 "generic" kernel:
$ systemd-analyze
Startup finished in 4.323s (kernel) + 11.189s (userspace) = 15.513s
graphical.target reached after 9.865s in userspace
5.5 "cloud" with optimizations:
$ systemd-analyze
Startup finished in 7.273s (kernel) + 21.984s (userspace) = 29.258s
graphical.target reached after 19.811s in userspace
$ systemd-analyze
Startup finished in 4.319s (kernel) + 13.684s (userspace) = 18.003s
graphical.target reached after 12.321s in userspace
$ systemd-analyze
Startup finished in 3.327s (kernel) + 9.846s (userspace) = 13.174s
graphical.target reached after 8.831s in userspace
The optimized timings are all taken from the initial boot of newly
launched instances.
It's certainly possible that things will look better with more data, but
it's not clear yet that this change is an improvement in all cases.
> > I'll post a WIP MR on salsa next. Some cleanup is needed still.
>
> Thank you for working on this!
>
The MR is here: https://salsa.debian.org/kernel-team/linux/merge_requests/206
I'm happy to share binary and/or source .debs and/or AMIs if you'd like
to run some of your own tests.
> Have you confirmed that with the optimizations, you can boot without
> needing an initramfs?
I've confirmed that the kernel can boot on c5 and t3 instances without
an initramfs present at all. However, the Xen backed EC2 instance types
would also need to statically link (at least) ATA_PIIX, ATA_GENERIC, and
XEN_BLKDEV_FRONTEND if we wanted to provide kernels that could be
generally useful in EC2 without an initramfs.
noah
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