On Fri, 9 Jun 2017 18:47:43 +0600
Yerden Zhumabekov <[email protected]> wrote:
> On 06.06.2017 19:19, Ananyev, Konstantin wrote:
> >
> >>>> Maybe there is some deeper reason for the >= 128-byte alignment logic
> >>>> in rte_ring.h?
> >>> Might be, would be good to hear opinion the author of that change.
> >> It gives improved performance for core-2-core transfer.
> > You mean empty cache-line(s) after prod/cons, correct?
> > That's ok but why we can't keep them and whole rte_ring aligned on
> > cache-line boundaries?
> > Something like that:
> > struct rte_ring {
> > ...
> > struct rte_ring_headtail prod __rte_cache_aligned;
> > EMPTY_CACHE_LINE __rte_cache_aligned;
> > struct rte_ring_headtail cons __rte_cache_aligned;
> > EMPTY_CACHE_LINE __rte_cache_aligned;
> > };
> >
> > Konstantin
> >
>
> I'm curious, can anyone explain, how does it actually affect
> performance? Maybe we can utilize it application code?
I think it is because on Intel CPU's the CPU will speculatively fetch adjacent
cache lines.
If these cache lines change, then it will create false sharing.
