Re: [PATCH v5] graph: expose node context as pointers

[Jerin Jacob <jerinjacobk@gmail.com>]

On Tue, Jun 25, 2024 at 9:02 PM Robin Jarry <rjarry@redhat.com> wrote:
>
> Sad :(
>
> > The introduced anonymous structure gets aligned on the minimum cache
> > line size (64 bytes): with this change, ctx[] move from offset 256, to
> > offset 192.
> > Similarly, nodes[] moves from offset 320 to offset 256.
> >
> > As we discussed offlist, there are a few options to workaround this
> > issue (like moving nodes[] inside the anonymous struct though it still
> > results in an increased rte_node struct, or like adding an explicit
> > padding field right before the newly introduced anonymous struct,
> > ...).
> [snip]
> > For those two reasons, it is better to revisit this patch and have it
> > ready for the next release.
> > While at it, it may be worth cleaning up the rte_node structure in
> > v24.11, if so, please announce in a deprecation notice for this
> > planned ABI breakage.
>
> Jerin, wouldn't it be better if we managed to fill in that 64 bytes
> hole?

It will be available only for 128B cache line system. So may not make sense.
I think, following change will resolve the issue in your patch.

From

 __extension__ struct __rte_cache_min_aligned {
 #define RTE_NODE_CTX_SZ 16

To

 __extension__ struct __rte_cache__aligned {
 #define RTE_NODE_CTX_SZ 16





>
> I don't know what to announce precisely about the breakage nature.
>