From: "Dumitrescu, Cristian" <cristian.dumitrescu@intel.com>
To: Olivier Matz <olivier.matz@6wind.com>,
"Pattan, Reshma" <reshma.pattan@intel.com>
Cc: "dev@dpdk.org" <dev@dpdk.org>,
"jerin.jacob@caviumnetworks.com" <jerin.jacob@caviumnetworks.com>,
"Rao, Nikhil" <nikhil.rao@intel.com>,
"thomas@monjalon.net" <thomas@monjalon.net>,
"Singh, Jasvinder" <jasvinder.singh@intel.com>
Subject: Re: [dpdk-dev] [PATCH v6 2/2] mbuf: implement generic format for sched field
Date: Thu, 20 Dec 2018 11:28:01 +0000 [thread overview]
Message-ID: <3EB4FA525960D640B5BDFFD6A3D891268E817B4F@IRSMSX108.ger.corp.intel.com> (raw)
In-Reply-To: <20181220082914.5hluj6nmn6s4rdrj@platinum>
Hi Olivier,
Thanks for your reply!
<snip>
> > * The generic rte_mbuf, containing a packet mbuf.
> > */
> > @@ -574,14 +585,16 @@ struct rte_mbuf {
> > * on PKT_RX_FDIR_* flag in ol_flags.
> > */
> > } fdir; /**< Filter identifier if FDIR enabled */
> > + struct rte_mbuf_sched sched; /**< Hierarchical
> scheduler */
>
>
> What about directly embedding the structure like the others? Since mbuf
> is a very packed structure, I think it helps to show that rte_mbuf_sched
> does not exceed the size of the union.
>
> I mean something like this:
>
> struct rte_mbuf_sched {
> uint32_t queue_id; /**< Queue ID. */
> uint8_t traffic_class;
> /**< Traffic class ID (0 = highest priority). */
> uint8_t color;
> /**< Color. @see enum rte_color. */
> uint16_t reserved; /**< Reserved. */
> } sched;
If this syntax does not limit the scope of struct rte_mbuf_sched to just within its parent struct rte_mbuf, then it would also fit my needs and I am more than happy to use it.
All I need is a name for this rte_mbuf_sched structure, so I can use it to get a decent implementation of set/get functions.
<snip>
> > + * @param m
> > + * Mbuf to read
> > + * @param queue_id
> > + * Returns the queue id
> > + * @param traffic_class
> > + * Returns the traffic class id
> > + * @param color
> > + * Returns the colour id
> > + */
> > +static inline void
> > +rte_mbuf_sched_get(const struct rte_mbuf *m, uint32_t *queue_id,
> > + uint8_t *traffic_class,
> > + uint8_t *color)
> > +{
> > + struct rte_mbuf_sched sched = m->hash.sched;
> > +
> > + *queue_id = sched.queue_id;
> > + *traffic_class = sched.traffic_class;
> > + *color = sched.color;
>
> I don't think there is a need to have an additional local copy.
>
> *queue_id = m->hash.sched.queue_id;
> *traffic_class = m->hash.sched.traffic_class;
> *color = m->hash.sched.color;
>
With local copy, compiler typically generates a single 8-byte read instruction. Without the local copy, compiler typically generates 3x read instructions.
The set/get functions are used in some performance critical actions, so this is the reason to make sure we get them right.
<snip>
> > + * @param m
> > + * Mbuf to set
> > + * @param queue_id
> > + * Queue id value to be set
> > + * @param traffic_class
> > + * Traffic class id value to be set
> > + * @param color
> > + * Color id to be set
> > + */
> > +static inline void
> > +rte_mbuf_sched_set(struct rte_mbuf *m, uint32_t queue_id,
> > + uint8_t traffic_class,
> > + uint8_t color)
> > +{
> > + m->hash.sched = (struct rte_mbuf_sched){
> > + .queue_id = queue_id,
> > + .traffic_class = traffic_class,
> > + .color = color,
> > + };
>
> Why not this?
>
> m->hash.sched.queue_id = queue_id;
> m->hash.sched.traffic_class = traffic_class;
> m->hash.sched.color = color;
>
Same here, we need the compiler to generate a single 8-byte write instruction rather than 3x read-modify-write operations. Makes sense?
>
> Apart from this, the mbuf part looks ok to me.
>
> Thanks,
> Olivier
Thanks,
Cristian
next prev parent reply other threads:[~2018-12-20 11:28 UTC|newest]
Thread overview: 74+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-23 16:54 [dpdk-dev] [PATCH] " Jasvinder Singh
2018-11-26 11:37 ` Dumitrescu, Cristian
2018-11-29 10:42 ` Singh, Jasvinder
2018-12-04 17:39 ` Dumitrescu, Cristian
2018-12-05 12:22 ` Singh, Jasvinder
2018-12-01 14:22 ` Jerin Jacob
2018-12-05 11:15 ` Singh, Jasvinder
2018-12-10 17:49 ` Dumitrescu, Cristian
2018-12-07 14:31 ` [dpdk-dev] [PATCH v2 1/3] " Reshma Pattan
2018-12-11 19:02 ` Dumitrescu, Cristian
2018-12-12 18:17 ` Dumitrescu, Cristian
2018-12-13 8:51 ` Rao, Nikhil
2018-12-13 18:08 ` [dpdk-dev] [PATCH v3 1/2] eal: add new rte color definition Reshma Pattan
2018-12-13 18:08 ` [dpdk-dev] [PATCH v3 2/2] mbuf: implement generic format for sched field Reshma Pattan
2018-12-14 22:52 ` Dumitrescu, Cristian
2018-12-20 8:32 ` Olivier Matz
2018-12-20 11:19 ` Dumitrescu, Cristian
2018-12-14 22:19 ` [dpdk-dev] [PATCH v3 1/2] eal: add new rte color definition Dumitrescu, Cristian
2018-12-17 20:35 ` Thomas Monjalon
2018-12-18 15:40 ` [dpdk-dev] [PATCH v4 1/2] meter: " Reshma Pattan
2018-12-18 15:40 ` [dpdk-dev] [PATCH v4 2/2] mbuf: implement generic format for sched field Reshma Pattan
2018-12-19 15:34 ` [dpdk-dev] [PATCH v5 1/2] meter: add new rte color definition Reshma Pattan
2018-12-19 15:34 ` [dpdk-dev] [PATCH v5 2/2] mbuf: implement generic format for sched field Reshma Pattan
2018-12-19 15:42 ` [dpdk-dev] [PATCH v6 1/2] meter: add new rte color definition Reshma Pattan
2018-12-19 15:42 ` [dpdk-dev] [PATCH v6 2/2] mbuf: implement generic format for sched field Reshma Pattan
2018-12-19 18:14 ` Ananyev, Konstantin
2018-12-20 8:29 ` Olivier Matz
2018-12-20 11:28 ` Dumitrescu, Cristian [this message]
2018-12-20 12:41 ` Olivier Matz
2018-12-20 12:16 ` [dpdk-dev] [PATCH v7 1/2] meter: add new rte color definition Reshma Pattan
2018-12-20 12:16 ` [dpdk-dev] [PATCH v7 2/2] mbuf: implement generic format for sched field Reshma Pattan
2018-12-20 12:43 ` Olivier Matz
2018-12-20 19:11 ` Dumitrescu, Cristian
2018-12-20 14:55 ` Rao, Nikhil
2019-01-15 22:37 ` Stephen Hemminger
2019-01-16 9:19 ` Pattan, Reshma
2019-01-16 9:33 ` Dumitrescu, Cristian
2019-01-16 10:09 ` Singh, Jasvinder
2019-01-15 23:11 ` Stephen Hemminger
2019-01-16 8:41 ` Thomas Monjalon
2018-12-07 14:31 ` [dpdk-dev] [PATCH v2 2/3] eal: add new rte color definition Reshma Pattan
2018-12-10 18:24 ` Dumitrescu, Cristian
2018-12-14 23:35 ` Ananyev, Konstantin
2018-12-15 0:16 ` Dumitrescu, Cristian
2018-12-17 11:21 ` Ananyev, Konstantin
2018-12-17 17:15 ` Pattan, Reshma
2018-12-17 18:51 ` Dumitrescu, Cristian
2018-12-17 23:11 ` Thomas Monjalon
2018-12-18 10:30 ` Dumitrescu, Cristian
2018-12-18 11:18 ` Dumitrescu, Cristian
2018-12-18 12:38 ` Thomas Monjalon
2018-12-18 13:19 ` Dumitrescu, Cristian
2018-12-18 13:39 ` Thomas Monjalon
2018-12-18 17:07 ` Ananyev, Konstantin
2018-12-18 19:34 ` Dumitrescu, Cristian
2018-12-18 20:19 ` Thomas Monjalon
2018-12-19 10:47 ` Dumitrescu, Cristian
2018-12-19 10:50 ` Thomas Monjalon
2018-12-19 10:52 ` Ananyev, Konstantin
2018-12-19 10:49 ` Ananyev, Konstantin
2018-12-19 11:04 ` Dumitrescu, Cristian
2018-12-18 10:15 ` Ananyev, Konstantin
2018-12-18 10:25 ` Pattan, Reshma
2018-12-18 10:38 ` Ananyev, Konstantin
2018-12-18 10:41 ` Pattan, Reshma
2018-12-18 10:52 ` Singh, Jasvinder
2018-12-18 12:10 ` Ananyev, Konstantin
2018-12-15 14:15 ` Mattias Rönnblom
2018-12-17 7:27 ` Pattan, Reshma
2018-12-17 9:41 ` Dumitrescu, Cristian
2018-12-17 19:36 ` Mattias Rönnblom
2018-12-17 23:24 ` Ferruh Yigit
2018-12-07 14:31 ` [dpdk-dev] [PATCH v2 3/3] doc: add deprecation notice to remove rte meter color Reshma Pattan
2018-12-11 14:58 ` Dumitrescu, Cristian
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