Re: [PATCH] tracing: Cleanup the convoluted softirq tracepoints

[Mathieu Desnoyers]

* H. Peter Anvin (hpa@xxxxxxxxx) wrote:
> On 10/20/2010 08:27 AM, Jason Baron wrote:
> > 
> > sure. The idea of the 'jmp 0' was simply to be an lcd for x86, if
> > there's a better lcd for x86, I'll update it. But note, that since the
> > 'jmp 0' is patched to a better nop at boot, we wouldn't see much gain.
> > And in the boot path we are using 'text_poke_early()', so avoiding that
> > isn't going to improve things much.
> > 
> 
> It's still a completely unnecessary waste of startup time some
> potentially significant fraction of the time.  Startup time matters,
> especially as the number of tracepoints grow.

We're still waiting for input for the best single-5-byte-instruction nop that
will work on all x86 variants. Please note that the GENERIC_NOP5 is actually two
instructions one next to each other, which is not appropriate here.

Thanks,

Mathieu

-- 
Mathieu Desnoyers
Operating System Efficiency R&D Consultant
EfficiOS Inc.
http://www.efficios.com
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