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SubjectRe: [PATCH] tracing: Cleanup the convoluted softirq tracepoints
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On Wed, 2010-10-20 at 00:17 +0200, Thomas Gleixner wrote:
> On Tue, 19 Oct 2010, Thomas Gleixner wrote:
> > On Tue, 19 Oct 2010, Jason Baron wrote:
> > > > Now even worse, when you NOP out the jmpq then your tracepoint is
> > > > still not enabled. Brilliant !
> > > >
> > >
> > > The 'jmpq' in the enabled case is patched with a jmpq to the body of the
> > > tracepoint itself.
> >
> > Brilliant.
>
> IOW, We now jump around the jump which jumps around the disabled code.
>


Do you happen to have CONFIG_CC_OPTIMIZE_FOR_SIZE set? If so, then this
is a known issue. We even originally had jump label enabled _only_ if
CC_OPTIMIZE_FOR_SIZE was not set, but hpa NAK'd it.

http://lkml.org/lkml/2010/9/22/482

http://lkml.org/lkml/2010/9/20/488

http://lkml.org/lkml/2010/9/24/259

-- Steve




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