RE: [PATCH v5] enhance NUMA affinity heuristic

["You, KaisenX" <kaisenx.you@intel.com>]

> -----Original Message-----
> From: Thomas Monjalon <thomas@monjalon.net>
> Sent: 2023年4月19日 20:17
> To: You, KaisenX <kaisenx.you@intel.com>
> Cc: dev@dpdk.org; Zhou, YidingX <yidingx.zhou@intel.com>;
> david.marchand@redhat.com; Matz, Olivier <olivier.matz@6wind.com>;
> ferruh.yigit@amd.com; zhoumin@loongson.cn; stable@dpdk.org;
> Richardson, Bruce <bruce.richardson@intel.com>; jerinj@marvell.com;
> Burakov, Anatoly <anatoly.burakov@intel.com>
> Subject: Re: [PATCH v5] enhance NUMA affinity heuristic
> 
> 13/04/2023 02:56, You, KaisenX:
> > From: You, KaisenX
> > > From: Thomas Monjalon <thomas@monjalon.net>
> > > >
> > > > I'm not comfortable with this patch.
> > > >
> > > > First, there is no comment in the code which helps to understand the
> logic.
> > > > Second, I'm afraid changing the value of the per-core variable
> > > > _socket_id may have an impact on some applications.
> > > >
> > Hi Thomas, I'm sorry to bother you again, but we can't think of a
> > better solution for now, would you please give me some suggestion, and
> then I will modify it accordingly.
> 
> You need to better explain the logic
> both in the commit message and in code comments.
> When it will be done, it will be easier to have a discussion with other
> maintainers and community experts.
> Thank you
> 
Thank you for your reply, I'll explain my patch in more detail next.

When a DPDK application is started on only one numa node, memory is allocated 
for only one socket.When interrupt threads use memory, memory may not be found 
on the socket where the interrupt thread is currently located, and memory has to be 
reallocated on the hugepage, this operation can lead to performance degradation.

So my modification is in the function malloc_get_numa_socket to make sure 
that the first socket with memory can be returned.

If you can accept my explanation and modification, I will send the V6 
version to improve the commit message and code comments.

> > > Thank you for your reply.
> > > First, about comments, I can submit a new patch to add comments to
> > > help understand.
> > > Second, if you do not change the value of the per-core variable_
> > > socket_ id, /lib/eal/common/malloc_heap.c
> > > malloc_get_numa_socket(void)
> > > {
> > >         const struct internal_config *conf = eal_get_internal_configuration();
> > >         unsigned int socket_id = rte_socket_id();   // The return value of
> > > "rte_socket_id()" is 1
> > >         unsigned int idx;
> > >
> > >         if (socket_id != (unsigned int)SOCKET_ID_ANY)
> > >                 return socket_id;    //so return here
> > >
> > > This will cause return here, This function returns the socket_id of
> > > unallocated memory.
> > >
> > > If you have a better solution, I can modify it.
> 
> 
>