Re: [RFC][PATCH 3/2] x86/jump labels: Count and display the shortjumps used

From: Steven Rostedt
Date: Wed Aug 07 2013 - 16:33:33 EST

On Wed, 2013-08-07 at 16:19 -0400, Jason Baron wrote:

> The whole point of the thread started with wanting to move the default
> 'disabled' branch further out-of-line. We could get there with better
> compiler support for the 'cold' label attribute. Thus, in theory the
> whole 2-byte jmp is just an intermediate step. (Yeah, I know that
> support doesn't seem to be happening anytime soon...)

Actually, Ideally, we would move the bulk of the tracing code out of
line, but we can have the jump to the tracing code still in line, and
the nop jump to it.

[ hot path]
jmp trace / nop


jmp trace_main_code
jmp 1b

Then that jmp trace can still be a 2 byte op.

-- Steve

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