Modern network hardware has often sprouted various "offload"
engines, unfortunately now often enabled by default, which tend to
do more damage than good except for extreme benchmarking fanatics,
often primarily on big server machines in data centers. Start by
turning them off. We'll write more on this topic soon. The
implementors of this "smart" hardware are less "smart" than they
think they are.
on CoDel benchmarking best practices
When we enter the kernel mode, we start with saving CPU state.
Usually (and you are going to hate that word well before you read
to the end) it's stored in struct pt_regs, but it might be more
complicated. For our purposes it's better to think of it as
abstract saved state, leaving aside the question of how it's
— Al Viro
teaches a class on signal
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