[dpdk-dev] [PATCH 2/2] net/qede: fix default config option

[Mody, Rasesh]

Hi Ferruh,

> From: Ferruh Yigit [mailto:ferruh.yigit at intel.com]
> Sent: Thursday, November 09, 2017 5:07 PM
> 
> On 11/9/2017 3:16 PM, Patil, Harish wrote:
> > -----Original Message-----
> > From: Ferruh Yigit <ferruh.yigit at intel.com>
> > Date: Thursday, November 9, 2017 at 4:07 PM
> > To: Harish Patil <Harish.Patil at cavium.com>, "Mody, Rasesh"
> > <Rasesh.Mody at cavium.com>, "dev at dpdk.org" <dev at dpdk.org>,
> > "thomas.monjalon at 6wind.com" <thomas.monjalon at 6wind.com>
> > Cc: Dept-Eng DPDK Dev <Dept-EngDPDKDev at cavium.com>
> > Subject: Re: [dpdk-dev] [PATCH 2/2] net/qede: fix default config
> > option
> >
> >> On 11/9/2017 3:00 PM, Patil, Harish wrote:
> >>> -----Original Message-----
> >>> From: Harish Patil <Harish.Patil at cavium.com>
> >>> Date: Thursday, November 9, 2017 at 3:57 PM
> >>> To: Ferruh Yigit <ferruh.yigit at intel.com>, "Mody, Rasesh"
> >>> <Rasesh.Mody at cavium.com>, "dev at dpdk.org" <dev at dpdk.org>,
> >>> "thomas.monjalon at 6wind.com" <thomas.monjalon at 6wind.com>
> >>> Cc: Dept-Eng DPDK Dev <Dept-EngDPDKDev at cavium.com>
> >>> Subject: Re: [dpdk-dev] [PATCH 2/2] net/qede: fix default config
> >>> option
> >>>
> >>>> -----Original Message-----
> >>>> From: Ferruh Yigit <ferruh.yigit at intel.com>
> >>>> Date: Thursday, November 9, 2017 at 3:48 PM
> >>>> To: "Mody, Rasesh" <Rasesh.Mody at cavium.com>, "dev at dpdk.org"
> >>>> <dev at dpdk.org>, "thomas.monjalon at 6wind.com"
> >>>> <thomas.monjalon at 6wind.com>
> >>>> Cc: Harish Patil <Harish.Patil at cavium.com>, Dept-Eng DPDK Dev
> >>>> <Dept-EngDPDKDev at cavium.com>
> >>>> Subject: Re: [dpdk-dev] [PATCH 2/2] net/qede: fix default config
> >>>> option
> >>>>
> >>>>> On 11/8/2017 10:52 PM, Rasesh Mody wrote:
> >>>>>> From: Harish Patil <harish.patil at cavium.com>
> >>>>>>
> >>>>>> Restore the default configuration as in previous releases and add
> >>>>>> a debug msg.
> >>>>>
> >>>>> Is this reverting
> >>>>> "f07aa795c92a ("net/qede: disable per-VF Tx switching feature")"
> >>>>>
> >>>>> This will be same as code before f07aa795c92a , right? If so why
> >>>>> not just remove the config option for this release and add a
> >>>>> dynamic runtime in next release?
> >>>>>
> >>>>> I am not clear for both f07aa795c92a and this one fixing, and why
> >>>>> should they be included for rc3?
> >>>>>
> >>>>> Thanks,
> >>>>> Ferruh
> >>>>
> >>>> Hi Ferruh,
> >>>> Some customers are interested in getting better performance with
> >>>> 64B sized packets. For that, they would need to keep this config
> >>>> disabled.
> >>>> But in all other cases, by default, we would like to keep Tx
> >>>> switching enabled (at a reduced performance) as in previous releases.
> >>>> As stated in other email with Thomas, we shall remove this
> >>>> compile-time config option in next release and use runtime option
> instead.
> >>>> But for 17.08 we need it to be enabled by default.
> >>>> Thanks.
> >>>
> >>> Correction, I meant 17.11 release, not 17.08.
> >>
> >> Other patch just sent two days ago, to introduce the config option as
> >> disabled by default, so it was changing the behavior and accepted as
> >> a fix for rc3.
> >>
> >> Now two days later, this patch enables it as a fix again, only
> >> difference for two days ago becomes adding a config option?
> >>
> >
> > Hi Ferruh,
> > The patch sent two days ago with config option disabled was a mistake.
> > Yesterday we realized that it is not a desirable thing to keep the
> > config disabled since many customers would typically need Tx switching
> > to be enabled.
> 
> I am trying to say, if you want to revert back and turn to original code, why
> not completely revert, removing config option too?

We have an issue where we see low numbers with 64 byte frames and is seen when "per-VF Tx switching" feature is enabled (which is the default behavior without the config option). To get better performance with small sized frames, the fix is to disable the Tx switching feature. We need to have the config option as a hotfix as it provides a means to disable "per-VF Tx switching" feature and achieve better performance with small sized frames. In other words, it provides end user with an option to enable a feature or get better small packet performance.

We also need this config option to be picked in DPDK 17.08 stable, which exhibits same behavior.

Thanks!
-Rasesh

> 
> Specially taking into account that you will remove it next release already.
> 
> > So the current patch we sent is just to change back the config option
> > set to enable from disable. Hence its a fix for the previous patch.
> 
> The cumulative output of both patches are adding a config option that
> doesn't change code execution by default. Overall output is not a fix.
> What do you think about a full revert of previous patch?
> 
> > Thanks.
> >>>>
> >>>>>
> >>>>>>
> >>>>>> Fixes: f07aa795c92a ("net/qede: disable per-VF Tx switching
> >>>>>> feature")
> >>>>>>
> >>>>>> Signed-off-by: Harish Patil <harish.patil at cavium.com>
> >>>>>> Signed-off-by: Rasesh Mody <rasesh.mody at cavium.com>
> >>>>>> ---
> >>>>>>  config/common_base             |    2 +-
> >>>>>>  drivers/net/qede/qede_ethdev.c |    5 +++--
> >>>>>>  2 files changed, 4 insertions(+), 3 deletions(-)
> >>>>>>
> >>>>>> diff --git a/config/common_base b/config/common_base index
> >>>>>> 34f04a9..e74febe 100644
> >>>>>> --- a/config/common_base
> >>>>>> +++ b/config/common_base
> >>>>>> @@ -415,7 +415,7 @@ CONFIG_RTE_LIBRTE_QEDE_DEBUG_INFO=n
> >>>>>>  CONFIG_RTE_LIBRTE_QEDE_DEBUG_DRIVER=n
> >>>>>>  CONFIG_RTE_LIBRTE_QEDE_DEBUG_TX=n
> >>>>>> CONFIG_RTE_LIBRTE_QEDE_DEBUG_RX=n
> >>>>>> -CONFIG_RTE_LIBRTE_QEDE_VF_TX_SWITCH=n
> >>>>>> +CONFIG_RTE_LIBRTE_QEDE_VF_TX_SWITCH=y
> >>>>>>  #Provides abs path/name of the firmware file.
> >>>>>>  #Empty string denotes driver will use default firmware
> >>>>>> CONFIG_RTE_LIBRTE_QEDE_FW=""
> >>>>>> diff --git a/drivers/net/qede/qede_ethdev.c
> >>>>>> b/drivers/net/qede/qede_ethdev.c index 8832145..6f5ba2a 100644
> >>>>>> --- a/drivers/net/qede/qede_ethdev.c
> >>>>>> +++ b/drivers/net/qede/qede_ethdev.c
> >>>>>> @@ -457,6 +457,7 @@ int qede_activate_vport(struct rte_eth_dev
> >>>>>> *eth_dev, bool flg)
> >>>>>>  	if (IS_VF(edev)) {
> >>>>>>  		params.update_tx_switching_flg = 1;
> >>>>>>  		params.tx_switching_flg = !flg;
> >>>>>> +		DP_INFO(edev, "VF tx-switching is disabled\n");
> >>>>>>  	}
> >>>>>>  #endif
> >>>>>>  	for_each_hwfn(edev, i) {
> >>>>>> @@ -469,8 +470,8 @@ int qede_activate_vport(struct rte_eth_dev
> >>>>>> *eth_dev, bool flg)
> >>>>>>  			break;
> >>>>>>  		}
> >>>>>>  	}
> >>>>>> -	DP_INFO(edev, "vport %s VF tx-switch %s\n", flg ?
> "activated" :
> >>>>>> "deactivated",
> >>>>>> -			params.tx_switching_flg ? "enabled" :
> "disabled");
> >>>>>> +	DP_INFO(edev, "vport is %s\n", flg ? "activated" :
> >>>>>> +"deactivated");
> >>>>>> +
> >>>>>>  	return rc;
> >>>>>>  }
> >>>>>>
> >>>>>>
> >>>>>
> >>>>
> >>>
> >>
> >