Re: [dpdk-dev] [PATCH RFC] eal: change default per socket memory allocation

[Thomas Monjalon <thomas.monjalon@6wind.com>]

2014-05-06 10:05, Burakov, Anatoly:
> David Marchand:
> > Actually, if we don't care where memory is allocated, we can at least try
> > to have the more common setup work properly (i.e. spread memory
> > allocations based on used cores).
> > I can see no usual setup where you
> > want to use cores on a socket while having all memory on another socket
> > but still expect performance to be good. 
> > So here is another approach for Didier's patch.
> > We can try to spread memory on numa sockets, if this fails, then we
> > default to previous behavior but leave a trace with a warning log "Could
> > not spread memory on numa sockets".
> > What do you think about this ?
> 
> Sounds like an overcomplication to me. There could be cases where
> performance doesn't matter, for example the -m switch could be used to run
> various tests (unit tests, functional tests etc.). For anything
> performance-related, the recommended option is to use --socket-mem,
> especially if you have NICs on specific sockets. Presumably, when you're
> setting up a coremask, you already know which sockets your cores are on, so
> I don't see a problem with specifying which sockets you want memory from.

Having --socket-mem option to explicitly configure NUMA is OK.
Having -m option for simple configuration is OK.
Making -m option working for most use cases would be really nice.
So I don't understand why we shouldn't do this enhancement. I don't know if 
"overcomplication" is a good argument. Maybe we should wait the patch to 
discuss it.

-- 
Thomas