Re: [PATCH v5] enhance NUMA affinity heuristic

[Thomas Monjalon <thomas@monjalon.net>]

21/04/2023 04:34, You, KaisenX:
> From: Thomas Monjalon <thomas@monjalon.net>
> > 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,

What do you mean by started on only one 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,

Why interrupt thread is on a different socket?

> 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.