Re: [PATCH v12 09/11] pvqspinlock, x86: Add para-virtualization support

From: Mike Galbraith
Date: Sat Oct 25 2014 - 14:22:03 EST


On Sat, 2014-10-25 at 00:04 +0200, Peter Zijlstra wrote:
> On Fri, Oct 24, 2014 at 04:53:27PM -0400, Waiman Long wrote:
> > The additional register pressure may just cause a few more register moves
> > which should be negligible in the overall performance . The additional
> > icache pressure, however, may have some impact on performance. I was trying
> > to balance the performance of the pv and non-pv versions so that we won't
> > penalize the pv code too much for a bit more performance in the non-pv code.
> > Doing it your way will add a lot of function call and register
> > saving/restoring to the pv code.
>
> If people care about performance they should not be using virt crap :-)

I tried some benching recently.. where did they hide the fastpaths? :)

-Mike

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