Re: [dpdk-dev] [PATCH v2 3/3] examples/ethtool: add control interface support to the application

["Yigit, Ferruh" <ferruh.yigit@intel.com>]

On Wed, Feb 17, 2016 at 07:39:05PM +0000, Ananyev, Konstantin wrote:
> Hi Ferruh,
> 
> > -----Original Message-----
> > From: dev [mailto:dev-bounces@dpdk.org] On Behalf Of Ferruh Yigit
> > Sent: Friday, February 12, 2016 1:46 PM
> > To: dev@dpdk.org
> > Subject: [dpdk-dev] [PATCH v2 3/3] examples/ethtool: add control interface support to the application
> > 
> > Control interface APIs added into the sample application.
> > 
> > To have the support corresponding kernel module (KCP) needs to be inserted.
> > If kernel module is not there, application will run as it is without
> > kernel control path support.
> > 
> > When KCP module inserted, running application creates a virtual Linux
> > network interface (dpdk$) per DPDK port. This interface can be used by
> > traditional Linux tools.
> > 
> > Signed-off-by: Ferruh Yigit <ferruh.yigit@intel.com>
> > ---
> >  doc/guides/sample_app_ug/ethtool.rst | 41 ++++++++++++++++++++++++++++++++++++
> >  examples/ethtool/ethtool-app/main.c  | 10 +++++++--
> >  2 files changed, 49 insertions(+), 2 deletions(-)
> > 
> > diff --git a/doc/guides/sample_app_ug/ethtool.rst b/doc/guides/sample_app_ug/ethtool.rst
> > index 4d1697e..2174288 100644
> > --- a/doc/guides/sample_app_ug/ethtool.rst
> > +++ b/doc/guides/sample_app_ug/ethtool.rst
> > @@ -131,6 +131,47 @@ application`_. Individual call-back functions handle the detail
> >  associated with each command, which make use of the functions
> >  defined in the `Ethtool interface`_ to the DPDK functions.
> 
> There is ~100% code duplication between
> lib/librte_ctrl_if/rte_ethtool.c and examples/ethtool/lib/rte_ethtool.c
> That need to be addressed somehow.
> 
Yes you are right, there is dublication.
In next revision, I will move examples/ethtool/lib to lib/ folder
and update according both ctrl_if library and ethtool sample app use it

> > 
> > +Control Interface
> > +~~~~~~~~~~~~~~~~~
> > +
> > +If Kernel Control Path (KCP) kernel module (rte_kcp.ko) inserted,
> > +virtual interfaces created for each DPDK port for control purposes.
> > +
> > +Created interfaces are named as dpdk#, like:
> > +
> > +.. code-block:: console
> > +
> > +        # ifconfig dpdk0; ifconfig dpdk1
> > +        dpdk0: flags=4099<UP,BROADCAST,MULTICAST>  mtu 1500
> > +                ether 90:e2:ba:0e:49:b9  txqueuelen 1000  (Ethernet)
> > +                RX packets 0  bytes 0 (0.0 B)
> > +                RX errors 0  dropped 0  overruns 0  frame 0
> > +                TX packets 0  bytes 0 (0.0 B)
> > +                TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0
> > +
> > +        dpdk1: flags=4099<UP,BROADCAST,MULTICAST>  mtu 1500
> > +                ether 00:1b:21:76:fa:21  txqueuelen 1000  (Ethernet)
> > +                RX packets 0  bytes 0 (0.0 B)
> > +                RX errors 0  dropped 0  overruns 0  frame 0
> > +                TX packets 0  bytes 0 (0.0 B)
> > +                TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0
> > +
> > +Regular Linux commands can be issued on interfaces:
> > +
> > +.. code-block:: console
> > +
> > +        # ethtool -i dpdk0
> > +        driver: rte_ixgbe_pmd
> > +        version: RTE 2.3.0-rc0
> > +        firmware-version:
> > +        expansion-rom-version:
> > +        bus-info: 0000:08:00.1
> > +        supports-statistics: yes
> > +        supports-test: no
> > +        supports-eeprom-access: yes
> > +        supports-register-dump: yes
> > +        supports-priv-flags: no
> > +
> >  Ethtool interface
> >  -----------------
> > 
> > diff --git a/examples/ethtool/ethtool-app/main.c b/examples/ethtool/ethtool-app/main.c
> > index e21abcd..68b13ad 100644
> > --- a/examples/ethtool/ethtool-app/main.c
> > +++ b/examples/ethtool/ethtool-app/main.c
> > @@ -1,7 +1,7 @@
> >  /*-
> >   *   BSD LICENSE
> >   *
> > - *   Copyright(c) 2015 Intel Corporation. All rights reserved.
> > + *   Copyright(c) 2016 Intel Corporation. All rights reserved.
> >   *   All rights reserved.
> >   *
> >   *   Redistribution and use in source and binary forms, with or without
> > @@ -44,6 +44,7 @@
> >  #include <rte_memory.h>
> >  #include <rte_mempool.h>
> >  #include <rte_mbuf.h>
> > +#include <rte_ctrl_if.h>
> > 
> >  #include "ethapp.h"
> > 
> > @@ -54,7 +55,6 @@
> >  #define PKTPOOL_EXTRA_SIZE 512
> >  #define PKTPOOL_CACHE 32
> > 
> > -
> >  struct txq_port {
> >  	uint16_t cnt_unsent;
> >  	struct rte_mbuf *buf_frames[MAX_BURST_LENGTH];
> > @@ -254,6 +254,8 @@ static int slave_main(__attribute__((unused)) void *ptr_data)
> >  			}
> >  			rte_spinlock_unlock(&ptr_port->lock);
> >  		} /* end for( idx_port ) */
> > +		rte_eth_control_interface_process_msg(
> > +				RTE_ETHTOOL_CTRL_IF_PROCESS_MSG, 0);
> 
> 
> As I can see, few problems here:
> 1. Race condition was introduced between slave_main() and ethapp_main() -
> both can try to do dev_start()/dev_stop() or other intrusive things over the same port  
> simultaneously.
> 2. Better to avoid calling rte_eth_control_interface_process_msg() from RT code path
>      that doing RX/TX packets - it is too slow for that.
> 3. Right now - if you'll have to postpone any RX/TX on any ports when calling  rte_eth_control_interface_process_msg().
>      As it can't distinguish message for what particular port it is going to process.
>     Need to address it somehow - either add function that would return current message port_id,
>    or introduce a sync callback function and add is a parameter for  rte_eth_control_interface_process_msg() ,
>   or probably something else.
> 
I will address these in next version of the patch.

Thanks for the comments,
ferruh