> -----Original Message-----
> From: Ananyev, Konstantin
> Sent: Tuesday, May 21, 2019 10:21 AM
> To: Ergin, Mesut A <mesut.a.er...@intel.com>; Xing, Beilei
> <beilei.x...@intel.com>; Zhang, Qi Z <qi.z.zh...@intel.com>
> Cc: dev@dpdk.org
> Subject: RE: [dpdk-dev] [PATCH 2/3] net/i40e: add runtime option to disable
> vector rx
>
>
>
> > > > >
> > > > > >
> > > > > > Vector RX functions are not at feature parity with non-vector ones
> > > > > > and
> > > > > > currently the vector RX path is enabled by default. Hence, the only
> > > > > > option to force selection of non-vector variants and be able to
> > > > > > retain
> > > > > > functionality is to disable vector PMD globally at compile time via
> > > > > > the
> > > > > > config file option.
> > > > > >
> > > > > > This patch introduces a new runtime device config option named
> > > > > > disable-vec-rx to allow users to limit the driver to make a choice
> > > > > > among
> > > > > > non-vector RX functions, on a per device basis. This runtime option
> > > > > > defaults to a value of zero, allowing vector RX functions to be
> > > > > > selected (current behavior). When disable-vec-rx=1 is specified for
> > > > > > a
> > > > > > device, even if all the other requirements to select a vector RX
> > > > > > function are satisfied, the driver will still pick one out of the
> > > > > > appropriate non-vector RX functions.
> > > > >
> > > > > Not sure I understand the logic of that patch.
> > > > > If i40e RX PMD selects wrong RX function that doesn't provide
> > > > > requested by user functionality (which one?) -
> > > > > then it is a bug in i40e RX function selection code that needs to be
> > > > > fixed.
> > > > > No point to introduce some new config options for that.
> > > > > Konstantin
> > > > >
> > > > Current design of RX function selection for the PMDs make it an
> > > > initialization time deal. However, the first rte_flow request (thus the
> > > > need
> > > > to enable FD / RTE_FDIR_MODE_PERFECT) may come in at any point in
> > > > time, well after the RX function was selected (e.g., OVS does this when
> > > > the
> > > > first packet that can be offloaded arrives). The design in this patch
> > > > gives
> > > > such applications a choice to restrict possible RX functions to
> > > > non-vector
> > > > paths proactively.
> > >
> > > If you plan to use FD mode on your device, why not enable it
> > > at setup phase via rte_eth_dev_configure()?
> > > Then proper rx function would be selected.
> > >
> >
> > FDIR_MODE was designed to bind late automatically -- it is set when the
> > first
> > filter rule is parsed, and unset when the last rule is removed.
>
> Why is that, if you can define it at configuration stage, and RX function
> selection is based on it?
I don't know why it was designed that way -- maybe maintainers know the
historical context.
>
> > As there are likely
> > other features not yet supported by the vector path, it felt more
> > appropriate
> > to have a generic flag for applications to not choose vector path.
>
> Once again - if some vector RX doesn't support particular requested at config
> feature, it wouldn't be selected. If it is not the case, then it is a bug in
> rx function selection code and should be fixed, instead of introducing
> workaround flags.
>
In any case, this has to be tied to a command line option, either on the
application
side (i.e. OVS) or DPDK devargs side, since we don't want to hard code it to
limit
RX functions to non-vector ones application-wide at compile time.
As far as I can see, passing FDIR configuration via the rte_eth_conf struct:
struct rte_fdir_conf fdir_conf; /**< FDIR configuration. DEPRECATED */
was deprecated. I suspect in favor of the late binding design mentioned, but
again, I don't know the history on that. IMO, this made devargs a better choice.
> > In fact, the
> > proposed option is the dual of already shipping use-latest-supported-vec
> > flag that lets the apps do the opposite (i.e. choose the "most" vectorized
> path).
>
> I don't think that's the same thing.
> From my perspective 'use-latest-supported-vec' is to overcome HW limitations.
>
That's fine, we seem to have different opinions on them. To me, both are
runtime configuration options that let users select what RX functions they
prefer to use with their HW.
> In your case, as I can see, all you need is to declare to HW/PMD that you plan
> to use FD HW capabilities and proper RX function will be selected
> automatically
> (pretty much as with other HW offloads, TX cksum, RX multi-seg, etc.).
>
Offload configurations you mentioned can be passed on to DPDK from the
application via offloads field in rte_eth_conf, FD cannot.
>
> >
> > > >
> > > > > >
> > > > > > Signed-off-by: Mesut Ali Ergin <mesut.a.er...@intel.com>
> > > > > > ---
> > > > > > doc/guides/nics/i40e.rst | 14 +++++++++
> > > > > > drivers/net/i40e/i40e_ethdev.c | 70
> > > > > +++++++++++++++++++++++++++++++++++++++++-
> > > > > > drivers/net/i40e/i40e_ethdev.h | 1 +
> > > > > > drivers/net/i40e/i40e_rxtx.c | 4 +++
> > > > > > 4 files changed, 88 insertions(+), 1 deletion(-)
> > > > > >
> > > > > > diff --git a/doc/guides/nics/i40e.rst b/doc/guides/nics/i40e.rst
> > > > > > index a97484c..532cc64 100644
> > > > > > --- a/doc/guides/nics/i40e.rst
> > > > > > +++ b/doc/guides/nics/i40e.rst
> > > > > > @@ -183,6 +183,20 @@ Runtime Config Options
> > > > > >
> > > > > > -w 84:00.0,use-latest-supported-vec=1
> > > > > >
> > > > > > +- ``Disable RX Vector Functions `` (default ``vector RX enabled``)
> > > > > > +
> > > > > > + When config file option for the vector PMD is enabled, vector RX
> > > functions
> > > > > may
> > > > > > + be the default choice of the driver at device initialization
> > > > > > time, if
> certain
> > > > > > + conditions apply. However, vector RX functions may not always be
> > > > > > at
> > > > > feature
> > > > > > + parity with non-vector ones. In order to allow users to override
> vector
> > > RX
> > > > > > + function selection behavior at runtime, the ``devargs`` parameter
> > > > > > + ``disable-vec-rx`` is introduced, such that
> > > > > > +
> > > > > > + -w DBDF,disable-vec-rx=1
> > > > > > +
> > > > > > + would force driver to limit its choices to non-vector RX function
> variants
> > > for
> > > > > > + the device specified by the DBDF.
> > > > > > +
> > > > > > Vector RX Pre-conditions
> > > > > > ~~~~~~~~~~~~~~~~~~~~~~~~
> > > > > > For Vector RX it is assumed that the number of descriptor rings
> > > > > > will be
> a
> > > power
> > > > > > diff --git a/drivers/net/i40e/i40e_ethdev.c
> > > b/drivers/net/i40e/i40e_ethdev.c
> > > > > > index cab440f..19fbd23 100644
> > > > > > --- a/drivers/net/i40e/i40e_ethdev.c
> > > > > > +++ b/drivers/net/i40e/i40e_ethdev.c
> > > > > > @@ -44,6 +44,7 @@
> > > > > > #define ETH_I40E_SUPPORT_MULTI_DRIVER "support-multi-driver"
> > > > > > #define ETH_I40E_QUEUE_NUM_PER_VF_ARG "queue-num-per-vf"
> > > > > > #define ETH_I40E_USE_LATEST_VEC "use-latest-supported-vec"
> > > > > > +#define ETH_I40E_DISABLE_VEC_RX "disable-vec-rx"
> > > > > >
> > > > > > #define I40E_CLEAR_PXE_WAIT_MS 200
> > > > > >
> > > > > > @@ -410,6 +411,7 @@ static const char *const valid_keys[] = {
> > > > > > ETH_I40E_SUPPORT_MULTI_DRIVER,
> > > > > > ETH_I40E_QUEUE_NUM_PER_VF_ARG,
> > > > > > ETH_I40E_USE_LATEST_VEC,
> > > > > > + ETH_I40E_DISABLE_VEC_RX,
> > > > > > NULL};
> > > > > >
> > > > > > static const struct rte_pci_id pci_id_i40e_map[] = {
> > > > > > @@ -1263,6 +1265,68 @@ i40e_use_latest_vec(struct rte_eth_dev
> *dev)
> > > > > > return 0;
> > > > > > }
> > > > > >
> > > > > > +static int
> > > > > > +i40e_parse_disable_vec_rx_handler(__rte_unused const char *key,
> > > > > > + const char *value,
> > > > > > + void *opaque)
> > > > > > +{
> > > > > > + struct i40e_adapter *ad;
> > > > > > +
> > > > > > + ad = (struct i40e_adapter *)opaque;
> > > > > > +
> > > > > > + switch (atoi(value)) {
> > > > > > + case 0:
> > > > > > + /* Selection of RX vector functions left untouched*/
> > > > > > + break;
> > > > > > + case 1:
> > > > > > + /* Disable RX vector functions as requested*/
> > > > > > + ad->rx_vec_allowed = false;
> > > > > > + break;
> > > > > > + default:
> > > > > > + PMD_DRV_LOG(WARNING, "Value should be 0 or 1, set
> it as
> > > > > 1!");
> > > > > > + break;
> > > > > > + }
> > > > > > +
> > > > > > + return 0;
> > > > > > +}
> > > > > > +
> > > > > > +int
> > > > > > +i40e_disable_vec_rx(struct rte_eth_dev *dev)
> > > > > > +{
> > > > > > + struct i40e_adapter *ad =
> > > > > > + I40E_DEV_PRIVATE_TO_ADAPTER(dev->data-
> >dev_private);
> > > > > > + struct rte_kvargs *kvlist;
> > > > > > + int kvargs_count;
> > > > > > +
> > > > > > +
> > > > > > + if (!dev->device->devargs)
> > > > > > + return 0;
> > > > > > +
> > > > > > + kvlist = rte_kvargs_parse(dev->device->devargs->args,
> valid_keys);
> > > > > > + if (!kvlist)
> > > > > > + return -EINVAL;
> > > > > > +
> > > > > > + kvargs_count = rte_kvargs_count(kvlist,
> ETH_I40E_DISABLE_VEC_RX);
> > > > > > + if (!kvargs_count) {
> > > > > > + rte_kvargs_free(kvlist);
> > > > > > + return 0;
> > > > > > + }
> > > > > > +
> > > > > > + if (kvargs_count > 1)
> > > > > > + PMD_DRV_LOG(WARNING, "More than one argument
> \"%s\"
> > > > > and only "
> > > > > > + "the first invalid or last valid one is
> > > > > > used !",
> > > > > > + ETH_I40E_DISABLE_VEC_RX);
> > > > > > +
> > > > > > + if (rte_kvargs_process(kvlist, ETH_I40E_DISABLE_VEC_RX,
> > > > > > + i40e_parse_disable_vec_rx_handler,
> ad) < 0) {
> > > > > > + rte_kvargs_free(kvlist);
> > > > > > + return -EINVAL;
> > > > > > + }
> > > > > > +
> > > > > > + rte_kvargs_free(kvlist);
> > > > > > + return 0;
> > > > > > +}
> > > > > > +
> > > > > > #define I40E_ALARM_INTERVAL 50000 /* us */
> > > > > >
> > > > > > static int
> > > > > > @@ -1795,6 +1859,9 @@ i40e_dev_configure(struct rte_eth_dev
> *dev)
> > > > > > ad->tx_simple_allowed = true;
> > > > > > ad->tx_vec_allowed = true;
> > > > > >
> > > > > > + /* Check if users wanted to disable vector RX functions */
> > > > > > + i40e_disable_vec_rx(dev);
> > > > > > +
> > > > > > /* Only legacy filter API needs the following fdir config. So
> when the
> > > > > > * legacy filter API is deprecated, the following codes should
> also be
> > > > > > * removed.
> > > > > > @@ -12790,4 +12857,5 @@
> > > RTE_PMD_REGISTER_PARAM_STRING(net_i40e,
> > > > > > ETH_I40E_FLOATING_VEB_LIST_ARG
> "=<string>"
> > > > > > ETH_I40E_QUEUE_NUM_PER_VF_ARG
> > > > > "=1|2|4|8|16"
> > > > > > ETH_I40E_SUPPORT_MULTI_DRIVER "=1"
> > > > > > - ETH_I40E_USE_LATEST_VEC "=0|1");
> > > > > > + ETH_I40E_USE_LATEST_VEC "=0|1"
> > > > > > + ETH_I40E_DISABLE_VEC_RX "=0|1");
> > > > > > diff --git a/drivers/net/i40e/i40e_ethdev.h
> > > b/drivers/net/i40e/i40e_ethdev.h
> > > > > > index 9855038..906bfe9 100644
> > > > > > --- a/drivers/net/i40e/i40e_ethdev.h
> > > > > > +++ b/drivers/net/i40e/i40e_ethdev.h
> > > > > > @@ -1248,6 +1248,7 @@ int i40e_config_rss_filter(struct i40e_pf *pf,
> > > > > > struct i40e_rte_flow_rss_conf *conf, bool add);
> > > > > > int i40e_vf_representor_init(struct rte_eth_dev *ethdev, void
> > > *init_params);
> > > > > > int i40e_vf_representor_uninit(struct rte_eth_dev *ethdev);
> > > > > > +int i40e_disable_vec_rx(struct rte_eth_dev *dev);
> > > > > >
> > > > > > #define I40E_DEV_TO_PCI(eth_dev) \
> > > > > > RTE_DEV_TO_PCI((eth_dev)->device)
> > > > > > diff --git a/drivers/net/i40e/i40e_rxtx.c
> > > > > > b/drivers/net/i40e/i40e_rxtx.c
> > > > > > index 1489552..7e66f59 100644
> > > > > > --- a/drivers/net/i40e/i40e_rxtx.c
> > > > > > +++ b/drivers/net/i40e/i40e_rxtx.c
> > > > > > @@ -1736,6 +1736,10 @@ i40e_dev_rx_queue_setup_runtime(struct
> > > > > rte_eth_dev *dev,
> > > > > > */
> > > > > > ad->rx_bulk_alloc_allowed = true;
> > > > > > ad->rx_vec_allowed = true;
> > > > > > +
> > > > > > + /* Check if users wanted to disable vector RX functions
> */
> > > > > > + i40e_disable_vec_rx(dev);
> > > > > > +
> > > > > > dev->data->scattered_rx = use_scattered_rx;
> > > > > > if (use_def_burst_func)
> > > > > > ad->rx_bulk_alloc_allowed = false;
> > > > > > --
> > > > > > 2.7.4
