[dpdk-dev] [PATCH v5] eal: add cache-line demote support

Bruce Richardson bruce.richardson at intel.com
Thu Oct 8 11:02:43 CEST 2020


On Thu, Oct 08, 2020 at 09:09:52AM +0200, David Marchand wrote:
> On Thu, Oct 1, 2020 at 2:30 AM Omkar Maslekar <omkar.maslekar at intel.com> wrote:
> >
> > rte_cldemote is similar to a prefetch hint - in reverse. cldemote(addr)
> > enables software to hint to hardware that line is likely to be shared.
> > Useful in core-to-core communications where cache-line is likely to be
> > shared. ARM and PPC implementation is provided with NOP and can be added
> > if any equivalent instructions could be used for implementation on those
> > architectures.
> >
> > Signed-off-by: Omkar Maslekar <omkar.maslekar at intel.com>
> > Acked-by: Bruce Richardson <bruce.richardson at intel.com>
> 
> I find this "rte_cldemote" name too close to the Intel instruction,
> but I can see no complaint from other arch maintainers, so I guess
> everyone is happy with it.

It is very close, alright - though the name too does fairly well convey the
likely actual done by the instruction.. Is there a suggestion for a better,
more generic name.

> In any case, this is a new API, so it should be marked experimental.
> 
Agreed.

> As for unit tests, not sure there is much to do, maybe rename
> test_prefetch.c and call this new API too, wdyt?
> 
I'm not sure how much value this would provide, but it can be done.



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