Re: [PATCH] x86: make use of inc/dec conditional
From: Thomas Gleixner
Date: Wed Aug 19 2009 - 05:57:17 EST
On Wed, 19 Aug 2009, Jan Beulich wrote:
> >>> Thomas Gleixner <tglx@xxxxxxxxxxxxx> 19.08.09 11:06 >>>
> >You still do not tell on which machines the INC/DEC instructions
> >should be avoided and why. GCC avoiding it is not a convincing
> >argument.
>
> On Pentium4 (Prescott/Nocona) inc/dec not modifying the carry flag cause
> an extra instruction dependency on EFLAGS, and hence extra latency in
> when the instruction can be scheduled for execution.
Do we really care that much about those electronic heaters which are
scheduled for darwinistic extinction since their introduction ?
Thanks,
tglx
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