[dpdk-dev] [PATCH v2 01/12] ethdev: add API to query packet type filling info
Adrien Mazarguil
adrien.mazarguil at 6wind.com
Fri Jan 15 16:33:01 CET 2016
On Fri, Jan 15, 2016 at 03:11:18PM +0000, Ananyev, Konstantin wrote:
> Hi lads,
>
> > -----Original Message-----
> > From: dev [mailto:dev-bounces at dpdk.org] On Behalf Of Adrien Mazarguil
> > Sent: Friday, January 15, 2016 1:59 PM
> > To: Tan, Jianfeng
> > Cc: dev at dpdk.org
> > Subject: Re: [dpdk-dev] [PATCH v2 01/12] ethdev: add API to query packet type filling info
> >
> > Hi Jianfeng, a few comments below.
> >
> > On Fri, Jan 15, 2016 at 01:45:48PM +0800, Jianfeng Tan wrote:
> > > Add a new API rte_eth_dev_get_ptype_info to query wether/what packet type will
> > > be filled by given pmd rx burst function.
> > >
> > > Signed-off-by: Jianfeng Tan <jianfeng.tan at intel.com>
> > > ---
> > > lib/librte_ether/rte_ethdev.c | 20 ++++++++++++++++++++
> > > lib/librte_ether/rte_ethdev.h | 27 +++++++++++++++++++++++++++
> > > lib/librte_mbuf/rte_mbuf.h | 6 ++++++
> > > 3 files changed, 53 insertions(+)
> > >
> > > diff --git a/lib/librte_ether/rte_ethdev.c b/lib/librte_ether/rte_ethdev.c
> > > index ed971b4..cd34f46 100644
> > > --- a/lib/librte_ether/rte_ethdev.c
> > > +++ b/lib/librte_ether/rte_ethdev.c
> > > @@ -1614,6 +1614,26 @@ rte_eth_dev_info_get(uint8_t port_id, struct rte_eth_dev_info *dev_info)
> > > dev_info->driver_name = dev->data->drv_name;
> > > }
> > >
> > > +int
> > > +rte_eth_dev_get_ptype_info(uint8_t port_id, uint32_t ptype_mask,
> > > + uint32_t ptypes[], int num)
> > > +{
> > > + int ret, i, j;
> > > + struct rte_eth_dev *dev;
> > > + uint32_t all_ptypes[RTE_PTYPE_MAX_NUM];
> > > +
> > > + RTE_ETH_VALID_PORTID_OR_ERR_RET(port_id, -ENODEV);
> > > + dev = &rte_eth_devices[port_id];
> > > + RTE_FUNC_PTR_OR_ERR_RET(*dev->dev_ops->dev_ptype_info_get, -ENOTSUP);
> > > + ret = (*dev->dev_ops->dev_ptype_info_get)(dev, all_ptypes);
> > > +
> > > + for (i = 0, j = 0; i < ret && j < num; ++i)
> > > + if (all_ptypes[i] & ptype_mask)
> > > + ptypes[j++] = all_ptypes[i];
> > > +
> > > + return ret;
> > > +}
> >
> > It's a good thing that the size of ptypes[] can be provided, but I think num
> > should be passed to the dev_ptype_info_get() callback as well.
> >
> > If you really do not want to pass the size, you have to force the array type
> > size onto callbacks using a pointer to the array otherwise they look unsafe
> > (and are actually unsafe when not called from the rte_eth_dev wrapper),
> > something like this:
> >
> > int (*dev_ptype_info_get)(uint8_t port_id, uint32_t (*ptypes)[RTE_PTYPE_MAX_NUM]);
> >
> > In which case you might as well drop the num argument from
> > rte_eth_dev_get_ptype_info() to use the same syntax. That way there is no
> > need to allocate a ptypes array on the stack twice.
> >
> > But since people usually do not like this syntax, I think passing num and
> > letting callbacks check for overflow themselves on the user-provided ptypes
> > array directly is better. They have to return the total number of packet
> > types supported even when num is 0 (ptypes may be NULL in that case).
> >
> > I understand the result needs to be temporarily stored somewhere for
> > filtering and for that purpose the entire size must be known in advance,
> > hence my previous suggestion for rte_eth_dev_get_ptype_info() to return
> > the total number of ptypes and providing a separate function for filtering
> > a ptypes array for applications that need it:
> >
> > /* Return remaining number entries in ptypes[] after filtering it
> > * according to ptype_mask. */
> > int rte_eth_dev_ptypes_filter(uint32_t ptype_mask, uint32_t ptypes[], int num);
> >
> > Usage would be like:
> >
> > int ptypes_num = rte_eth_dev_get_ptype_info(42, NULL, 0);
> >
> > if (ptypes_num <= 0)
> > goto err;
> >
> > uint32_t ptypes[ptypes_num];
> >
> > rte_eth_dev_get_ptype_info(42, ptypes, ptypes_num);
> > ptypes_num = rte_eth_dev_ptypes_filter(RTE_PTYPE_INNER_L4_MASK, ptypes, ptypes_num);
> >
> > if (ptypes_num <= 0)
> > goto err;
> >
> > /* process ptypes... */
> >
> > What about this?
>
> Actually while thinking about it, we probably can make:
> const uint32_t * (*dev_ptype_info_get)(uint8_t port_id);
> So PMD return to ethdev layer a pointer to a constant array of supported ptypes,
> terminated by RTE_PTYPE_UNKNOWN.
>
> Then rte_eth_dev_get_ptype_info() will iterate over it, and fill array provided by the user.
>
> all_pytpes = (*dev->dev_ops->dev_ptype_info_get)(dev);
> for (i = 0; all_ptypes[i] != RTE_PTYPE_UNKNOWN; i++) {
> if (all_ptypes[i] & ptype_mask) {
> if (j < num)
> ptypes[j] = all_ptypes[i];
> j++;
> }
> return j;
Looks like a much simpler and better approach, that's the implementation we
need! (ignore my overengineered blob above)
--
Adrien Mazarguil
6WIND
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