Re: rte_memzone_reserve and invalid socket id

[Dmitry Kozlyuk <dmitry.kozliuk@gmail.com>]

2022-04-13 00:54 (UTC-0700), Tyler Retzlaff:
> On Mon, Mar 28, 2022 at 11:04:36PM -0700, Tyler Retzlaff wrote:
[...]
> > 	memzone3 = rte_memzone_reserve(TEST_MEMZONE_NAME("testzone3"), 1000,
> > 				1, 0);
> >                                 ^ socket_id (to repeat just make it invalid)
> > 
> > the parameter documentation provided for reference.
> > 
> >  * @param socket_id
> >  *   The socket identifier in the case of
> >  *   NUMA. The value can be SOCKET_ID_ANY if there is no NUMA
> >  *   constraint for the reserved zone.
> > 
> > of interest is should rte_memzone_reserve fail when provided a
> > completely invalid socket_id?

I think it should.

> > 
> > when running with --no-huge it does not because when --no-huge the
> > socket_id no matter the value is silently re-mapped to SOCKET_ID_ANY
> > though without --no-huge if a completely garbage socket_id were provided
> > it seems the allocation would fail.

It's an implementation detail.
NUMA could be respected for --no-huge if there was a need.

> > 
> > so you get different behavior for an invalid socket_id depending on
> > --no-huge vs with.
> > 
> > 	if (!rte_eal_has_hugepages() && socket_id < RTE_MAX_NUMA_NODES)
> > 		socket_id = SOCKET_ID_ANY;
> > 
> > the test later fails at this check. where it compares the memzone3
> > socket_id to what was used in the call to rte_memzone_reserve.
> > 
> > 	if (memzone3 != NULL && memzone3->socket_id != 1)
> > 		return -1;                ^ SOCKET_ID_ANY if --no-huge
> > 
> > if the allocation had failed, the test would pass instead of failing at
> > this point.
> > 
> > so what's wrong here? the test should be changed to expect different
> > behavior with --no-huge vs huge or should rte_memzone_reserve be
> > explicitly requiring SOCKET_ID_ANY instead of re-mapping invalid socket
> > id?

memzone3->socket_id == SOCKET_ID_ANY should not be possible,
because it's a specific selected socket ID.
Rather, the check should be relaxed depending on rte_eal_has_hugepages().