Re: [dpdk-dev] [PATCH v2 3/4] common_base: extend RTE_MAX_ETHPORTS from 32 to 1024

[Bruce Richardson <bruce.richardson@intel.com>]

On Mon, Sep 04, 2017 at 07:59:29AM +0000, Yang, Zhiyong wrote:
> Hi,  Lei:
> 
> > -----Original Message-----
> > From: Yao, Lei A
> > Sent: Monday, September 4, 2017 3:46 PM
> > To: Yang, Zhiyong <zhiyong.yang@intel.com>; dev@dpdk.org
> > Cc: thomas@monjalon.net; Yigit, Ferruh <ferruh.yigit@intel.com>; Wiles, Keith
> > <keith.wiles@intel.com>; stephen@networkplumber.org; Yang, Zhiyong
> > <zhiyong.yang@intel.com>
> > Subject: RE: [dpdk-dev] [PATCH v2 3/4] common_base: extend
> > RTE_MAX_ETHPORTS from 32 to 1024
> > 
> > 
> > 
> > > -----Original Message-----
> > > From: dev [mailto:dev-bounces@dpdk.org] On Behalf Of Zhiyong Yang
> > > Sent: Monday, September 4, 2017 1:58 PM
> > > To: dev@dpdk.org
> > > Cc: thomas@monjalon.net; Yigit, Ferruh <ferruh.yigit@intel.com>;
> > > Wiles, Keith <keith.wiles@intel.com>; stephen@networkplumber.org;
> > > Yang, Zhiyong <zhiyong.yang@intel.com>
> > > Subject: [dpdk-dev] [PATCH v2 3/4] common_base: extend
> > > RTE_MAX_ETHPORTS from 32 to 1024
> > >
> > > The reasons to modify RTE_MAX_ETHPORTS is the following.
> > >
> > > 1. RTE_MAX_ETHPORTS=32 by default has not met user's requirements with
> > > development of virtualization technology. Some vdev users have to
> > > modify the setting before the compiling.
> > >
> > > 2. port_id have been extended to 16 bits definition. But for many
> > > samples such as testpmd, l3fwd, num of port is still limited to
> > > RTE_MAX_ETHPORTS=32 by default. This may limit usage of 16 bits
> > > port_id.
> > >
> > > So, it is necessary to enlarge RTE_MAX_ETHPORTS to more than 256.
> > >
> > > Signed-off-by: Zhiyong Yang <zhiyong.yang@intel.com>
> > > ---
> > >  config/common_base | 2 +-
> > >  1 file changed, 1 insertion(+), 1 deletion(-)
> > >
> > > diff --git a/config/common_base b/config/common_base index
> > > 5e97a08b6..dccc13e31 100644
> > > --- a/config/common_base
> > > +++ b/config/common_base
> > > @@ -131,7 +131,7 @@ CONFIG_RTE_LIBRTE_KVARGS=y  #
> > > CONFIG_RTE_LIBRTE_ETHER=y  CONFIG_RTE_LIBRTE_ETHDEV_DEBUG=n
> > > -CONFIG_RTE_MAX_ETHPORTS=32
> > > +CONFIG_RTE_MAX_ETHPORTS=1024
> > >  CONFIG_RTE_MAX_QUEUES_PER_PORT=1024
> > >  CONFIG_RTE_LIBRTE_IEEE1588=n
> > >  CONFIG_RTE_ETHDEV_QUEUE_STAT_CNTRS=16
> > > --
> > > 2.13.3
> > Hi, Zhiyong
> > 
> > I met one issue for changing CONFIG_RTE_MAX_ETHPORTS to 1024.
> > One process can only open 1024 file as maximum in common linux distribution,
> > after practice, only 1009 socket file can be used for vdev device with testpmd
> > sample.
> 
> Thanks for your info.  It seems that 1024 is too large and may bring some potential issues.
> 
> Thanks
> Zhiyong
> 

It should be possible to have a dynamically allocated ethdev array,
which would allow use to have a default value - which could be e.g. 32
or 64 as now - while also allowing a run-time parameter to increase that
to thousands if needed.

/Bruce