[dpdk-dev] [PATCH] eal/ppc: remove fix of memory barrier for IBM POWER

[Thomas Monjalon]

22/03/2019 16:30, Pradeep Satyanarayana:
> Thomas Monjalon <thomas at monjalon.net> wrote on 03/22/2019 01:49:03 AM:
> > 22/03/2019 02:40, Pradeep Satyanarayana:
> > > - rte_[rw]mb (general memory barrier) --> should be lwsync
> >
> > This is what may be discussed.
> > The assumption is that the general memory barrier should cover
> > all cases (CPU caches, SMP and I/O).
> > That's why we think it should "sync" for Power.
> 
> In that case, at a minimum we must de-link rte_smp_[rw]mb from rte_[rw]mb
> and retain it as lwsync. Agreed?

I have no clue about what is needed for SMP barrier in Power.
As long as it works as expected, no problem.

> > > - rte_smp_[rw]mb (SMP memory barrier) -->should be lwsync
> > > - rte_io_[rw]mb (I/O memory barrier)  --> should be sync
> > > - rte_cio_[rw]mb (coherent I/O memory barrier) -->should be sync
> > >
> > > lwsync is appropriate for cases where CPUs are accessing cacheable
> > > memory (i.e. Memory Coherence Required) while the sync instruction
> > > should be used in all other cases.