* Andrew Morton <a...@linux-foundation.org> wrote:
> On Wed, 17 Jul 2013 09:21:00 +0200 Ingo Molnar <mi...@kernel.org> wrote:
>
> >
> > * Dave Hansen <d...@sr71.net> wrote:
> >
> > > I was investigating some TLB flush scaling issues and realized
> > > that we do not have any good methods for figuring out how many
> > > TLB flushes we are doing.
> > >
> > > It would be nice to be able to do these in generic code, but the
> > > arch-independent calls don't explicitly specify whether we
> > > actually need to do remote flushes or not. In the end, we really
> > > need to know if we actually _did_ global vs. local invalidations,
> > > so that leaves us with few options other than to muck with the
> > > counters from arch-specific code.
>
> Spose so, if you really think it's worth it. It's all downside for
> uniprocessor machines. [...]
UP is slowly going extinct, but in any case these counters ought to inform
us about TLB flushes even on UP systems:
> > > + NR_TLB_LOCAL_FLUSH_ALL,
> > > + NR_TLB_LOCAL_FLUSH_ONE,
> > > + NR_TLB_LOCAL_FLUSH_ONE_KERNEL,
While these ought to be compiled out on UP kernels:
> > > + NR_TLB_REMOTE_FLUSH, /* cpu tried to flush others' tlbs */
> > > + NR_TLB_REMOTE_FLUSH_RECEIVED,/* cpu received ipi for flush */
Right?
> > Please fix the vertical alignment of comments.
>
> I looked - this isn't practical.
>
> It would be nice to actually document these things though. We don't
> *have* to squeeze the comment into the RHS.
Agreed.
Thanks,
Ingo
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