Re: [dpdk-dev] [PATCH] eal: default to one memory channel if not specified

[David Marchand <david.marchand@6wind.com>]

Hello Panu,

On Wed, Oct 14, 2015 at 12:22 PM, Panu Matilainen <pmatilai@redhat.com>
wrote:

> Obtaining the correct value, especially from a running system, can
> be anything from difficult to plain impossible.  Since the value is
> merely an optimization and does not affect functionality otherwise,
> its pointless to force such a guess on users initially, such things
> belong to performance tuning phase.
>
> Signed-off-by: Panu Matilainen <pmatilai@redhat.com>
> ---
>  lib/librte_eal/common/eal_common_options.c | 10 ++--------
>  1 file changed, 2 insertions(+), 8 deletions(-)
>
> diff --git a/lib/librte_eal/common/eal_common_options.c
> b/lib/librte_eal/common/eal_common_options.c
> index 1f459ac..28f10a2 100644
> --- a/lib/librte_eal/common/eal_common_options.c
> +++ b/lib/librte_eal/common/eal_common_options.c
> @@ -104,7 +104,7 @@ eal_reset_internal_config(struct internal_config
> *internal_cfg)
>
>         internal_cfg->memory = 0;
>         internal_cfg->force_nrank = 0;
> -       internal_cfg->force_nchannel = 0;
> +       internal_cfg->force_nchannel = 1;
>

Well, not too sure about this default value.

- mempool code is already checking for the 0 value.
- API already tells for rte_memory_get_nchannel() :
 *
@return

 *   The number of memory channels on the system. The value is 0 if
unknown
 *   or not the same on all
devices.

So, I would let it 0.


-- 
David Marchand