Evaluate using Link-Time Optimization (LTO) and Profile-Guided Optimization (PGO)

[zamazan4ik]

Hi!

I have several ideas about how DragonOS's performance can be improved - maybe some of these ideas will be interesting enough for you to try them ;)

Firstly, I noticed that in the Cargo.toml file Link-Time Optimization (LTO) for the project is not enabled. I suggest switching it on since it will reduce the binary size (always a good thing to have) and will likely improve the application's performance a bit.

I suggest enabling LTO only for the Release builds so as not to sacrifice the developers' experience while working on the project since LTO consumes an additional amount of time to finish the compilation routine. If you think that a regular Release build should not be affected by such a change as well, then I suggest adding an additional dist or release-lto profile where additionally to regular release optimizations LTO also will be added. Such a change simplifies life for maintainers and others interested in the project persons who want to build the most performant version of the application. Using ThinLTO should also help.

As a next step, I kindly suggest evaluating Profile-Guided Optimization (PGO) and Post-Link Optimization (PLO) approaches. These optimizations allow you to optimize an application based on different runtime statistics. I have collected as much information about PGO and PLO here (including many benchmarks) as I can: https://github.com/zamazan4ik/awesome-pgo . This repository including PGO benchmarks for operating systems/kernels too like Windows and Linux.

I think all the optimizations above would be interesting for you since LTO and PGO are already integrated into the Linux kernel infrastructure and show good performance results in practice.

Thank you.