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    SubjectRe: {PATCH] Re: wasting time on page fault
    Andi Kleen wrote:
    > > 1. Move the error_code block from divide_error to page_fault;
    > > this removes one jump from the page_fault path.
    >
    > It is not clear that it is worth it. You want to align error_code and
    > page_fault to 16 or 32 bytes bytes at least, and it would need to execute
    > some nops depending on the length for fallthrough
    > The jmp may be actually faster.

    The assembler doesn't use nops for alignment -- it inserts longer
    instructions that are effectively nops, either 1 or two. For larger
    stretches, the assembler inserts a jmp itself for alignment.

    Regardless, I'd expect the page_fault path to occur far more often than
    any of the other fault/exception handlers that lead to error_code. So
    much more that not aligning error_code is probably the right thing to do.

    -- Jamie
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