Following up on this, here's a simplified list of optimizations for the cloud variant in one place, taking into account the previous reply. Would it help to get this in the form of a patch or MR on https://salsa.debian.org/kernel-team/linux/ ?
- Please compile in the NVME driver and the EXT4 filesystem; this will allow many cloud systems to avoid using an initramfs at all, which substantially improves boot time. - Please consider changing the default kernel compression to LZ4, which decompresses much faster and thus boots faster. (Benchmarks to support this: https://smackerelofopinion.blogspot.com/2019/09/ ) Please consider doing this on the non-cloud configuration as well. - Please disable CONFIG_ACPI_BGRT; a cloud kernel doesn't need to spend time or code space looking for a boot logo that won't exist. - Please disable the CONFIG_CPU_SUP_* options for CPUs that no cloud provider uses (concretely, please disable everything except CONFIG_CPU_SUP_AMD and CONFIG_CPU_SUP_INTEL). - Please disable CONFIG_GNSS_*, which won't be hooked up to a cloud server. - Please disable CONFIG_GTP for the same reason. - Please configure CONFIG_INPUT_MOUSEDEV as a module, not built-in, as most cloud servers won't have a mouse and probing for one takes time. - Please change CONFIG_NET_MPLS_GSO from y to m. While nothing will automatically load it, it's sufficiently rare that loading it manually seems reasonable, and this would reduce attack surface and boot time. - Please disable CONFIG_NUMA_EMU, only used to create fake-NUMA systems for debugging. - Please disable CONFIG_PCIPCWATCHDOG and CONFIG_RMI4_*, which won't appear on a cloud server. - Please enable CONFIG_SCHED_MC_PRIO (on both cloud and non-cloud kernels). - Please disable CONFIG_VFIO_PCI_VGA and CONFIG_VGA_SWITCHEROO, which won't appear on cloud. Thank you, Josh Triplett
