Re: [dpdk-dev] [EXT] Re: [PATCH 1/3] mbuf: add Tx offloads for packet marking

[Nithin Dabilpuram <ndabilpuram@marvell.com>]

On Tue, Jun 02, 2020 at 10:53:08AM +0000, Ananyev, Konstantin wrote:
> Hi Jerin,
> 
> > > > > I also share Olivier's concern about consuming 3 bits in ol_flags for that feature.
> > > > > Can it probably be squeezed somehow?
> > > > > Let say we reserve one flag that this information is present or not, and
> > > > > re-use one of rx-only fields for store additional information (packet_type, or so).
> > > > > Or might be some other approach.
> > > >
> > > > We are fine with this approach where we define one bit in Tx offloads for pkt
> > > > marking and and 3 bits reused from Rx offload flags area.
> > > >
> > > > For example:
> > > >
> > > > @@ -186,10 +186,16 @@ extern "C" {
> > > >
> > > >  /* add new RX flags here, don't forget to update PKT_FIRST_FREE */
> > > >
> > > > +/* Reused Rx offload bits for Tx offloads */
> > > > +#define PKT_X_TX_MARK_VLAN_DEI         (1ULL << 0)
> > > > +#define PKT_X_TX_MARK_IP_DSCP          (1ULL << 1)
> > > > +#define PKT_X_TX_MARK_IP_ECN           (1ULL << 2)
> > > > +
> > > >  #define PKT_FIRST_FREE (1ULL << 23)
> > > > -#define PKT_LAST_FREE (1ULL << 40)
> > > > +#define PKT_LAST_FREE (1ULL << 39)
> > > >
> > > >  /* add new TX flags here, don't forget to update PKT_LAST_FREE  */
> > > > +#define PKT_TX_MARK_EN         (1ULL << 40)
> > > >
> > > > Is this fine ?
> > >
> > > Any thoughts on this approach which uses only 1 bit in Tx flags out of 18
> > > and reuse unused Rx flag bits ?
> 
> My thought was not about re-defining the flags (I think it is better to keep them intact),
> but adding a union for one of rx-only fields (packet_type/rss/timestamp).

Ok. Adding a union field at packet_type field is also fine like below. 

@@ -187,9 +187,10 @@ extern "C" {
 /* add new RX flags here, don't forget to update PKT_FIRST_FREE */
 
 #define PKT_FIRST_FREE (1ULL << 23)
-#define PKT_LAST_FREE (1ULL << 40)
+#define PKT_LAST_FREE (1ULL << 39)
 
 /* add new TX flags here, don't forget to update PKT_LAST_FREE  */
+#define PKT_TX_MARK_EN		(1ULL << 40)
 
 /**
  * Outer UDP checksum offload flag. This flag is used for enabling
@@ -461,6 +462,14 @@ enum {
 #endif
 };
 
+/* Tx packet marking flags in rte_mbuf::tx_mark.
+ * Valid only when PKT_TX_MARK_EN is set in
+ * rte_mbuf::ol_flags.
+ */
+#define TX_MARK_VLAN_DEI	(1ULL << 0)
+#define TX_MARK_IP_DSCP	(1ULL << 1)
+#define TX_MARK_IP_ECN		(1ULL << 2)
+
 /**
  * The generic rte_mbuf, containing a packet mbuf.
  */
@@ -543,6 +552,10 @@ struct rte_mbuf {
 			};
 			uint32_t inner_l4_type:4; /**< Inner L4 type. */
 		};
+		struct {
+			uint32_t reserved:29;
+			uint32_t tx_mark:3;
+		};
 	};



Please correct me if this is not what you mean.

> 
> > 
> > + Techboard
> > 
> > There is a related thread going on
> > https://urldefense.proofpoint.com/v2/url?u=http-3A__mails.dpdk.org_archives_dev_2020-2DMay_168810.html&d=DwIGaQ&c=nKjWec2b6R0mOyPaz7xtfQ&r=FZ_tPCbgFOh18zwRPO9H0yDx8VW38vuapifdDfc8SFQ&m=nyV4Rud03HW6DbWMpyvOCulQNkagmfo0wKtrwQ7zmmg&s=VuktoUb_xoLsHKdB9mV87x67cP9tXk3DqVXptt9nF_s&e= 
> > 
> > If there is no consensus on email, then I would like to add this item
> > to the next TB meeting.
> 
> Ok, I'll add that to tomorrow meeting agenda.
> Konstantin
>