Re: [dpdk-dev] [PATCH v6 12/19] malloc: fix the issue of SOCKET_ID_ANY

["Liang, Cunming" <cunming.liang@intel.com>]

Hi,

> -----Original Message-----
> From: Neil Horman [mailto:nhorman@tuxdriver.com]
> Sent: Saturday, February 14, 2015 1:57 AM
> To: Liang, Cunming
> Cc: dev@dpdk.org
> Subject: Re: [dpdk-dev] [PATCH v6 12/19] malloc: fix the issue of SOCKET_ID_ANY
> 
> On Fri, Feb 13, 2015 at 09:38:14AM +0800, Cunming Liang wrote:
> > Add check for rte_socket_id(), avoid get unexpected return like (-1).
> >
> > Signed-off-by: Cunming Liang <cunming.liang@intel.com>
> > ---
> >  lib/librte_malloc/malloc_heap.h | 7 ++++++-
> >  1 file changed, 6 insertions(+), 1 deletion(-)
> >
> > diff --git a/lib/librte_malloc/malloc_heap.h b/lib/librte_malloc/malloc_heap.h
> > index b4aec45..a47136d 100644
> > --- a/lib/librte_malloc/malloc_heap.h
> > +++ b/lib/librte_malloc/malloc_heap.h
> > @@ -44,7 +44,12 @@ extern "C" {
> >  static inline unsigned
> >  malloc_get_numa_socket(void)
> >  {
> > -	return rte_socket_id();
> > +	unsigned socket_id = rte_socket_id();
> > +
> > +	if (socket_id == (unsigned)SOCKET_ID_ANY)
> > +		return 0;
> > +
> > +	return socket_id;
> Why is -1 unexpected?  Isn't it reasonable to assume that some memory is
> equidistant from all cpu numa nodes?
[LCM] One piece of memory will be whole allocated from one specific NUMA node. But won't be like some part from one and the other part from another.
If no specific NUMA node assigned(SOCKET_ID_ANY/-1), it firstly asks for the current NUMA node where current core belongs to.
'malloc_get_numa_socket()' is called on that time. When the time 1:1 thread/core mapping is assumed and the default value is 0, it always will return a none (-1) value.
Now rte_socket_id() may return -1 in the case the pthread runs on multi-cores which are not belongs to one NUMA node, or in the case _socket_id is not yet assigned and the default value is (-1). So if current _socket_id is -1, then just pick up the first node as the candidate. Probably I shall add more comments for this.
> 
> Neil
> 
> >  }
> >
> >  void *
> > --
> > 1.8.1.4
> >
> >