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Great work, thanks for sharing! Systems performance at its best. Nice to see the use of the custom palette.map (I forget to do that myself and I often end up hacking in highlights in the Perl code.)

BTW, those disconnected kernel stacks can probably be reconnected with the user stacks by switching out the libc for one with frame pointers; e.g., the new libc6-prof package.

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Thank you for sharing all your amazing tools and resources brendangregg! I wouldn't have been able to do most of these optimizations without FlameGraph and bpftrace.

I actually did the same thing and hacked up the perl code to generate the my custom palette.map

Thanks for the tip re: the disconnected kernel stacks. They actually kinda started to grow on me for this experiment, especially since most of the work was on the kernel side.

Is libc6-prof just glibc recompiled with -fno-omit-frame-pointer? I did that a couple times and found that while that fixes a few system calls, it doesn't fix all of them. I think the main issue was several syscalls being called from asm, which wasn't unsurprisingly isn't affected by -fno-omit-frame-pointer.

Right, it is. It fixed my hot-path syscalls on x86 (via read/write functions, pthread_mutex functions, etc.). But if you have syscalls called via asm outside of libc (by who?) then they need frame pointers as well.

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