From: Ivan Boule <ivan.boule@6wind.com>
To: "Ananyev, Konstantin" <konstantin.ananyev@intel.com>,
"Kulasek, TomaszX" <tomaszx.kulasek@intel.com>,
"dev@dpdk.org" <dev@dpdk.org>
Subject: Re: [dpdk-dev] [PATCH 1/2] ethdev: add buffered tx api
Date: Fri, 12 Feb 2016 17:40:02 +0100 [thread overview]
Message-ID: <56BE0AE2.8080305@6wind.com> (raw)
In-Reply-To: <2601191342CEEE43887BDE71AB97725836B062E2@irsmsx105.ger.corp.intel.com>
On 02/12/2016 12:44 PM, Ananyev, Konstantin wrote:
>
>>
>>> -----Original Message-----
...
>>
>> In that case we don't need to make any changes at rte_ethdev.[h,c] to alloc/free/maintain tx_buffer inside each queue...
>> It all will be upper layer responsibility.
>> So no need to modify existing rte_ethdev structures/code.
>> Again, no need for error callback - caller would check return value and decide what to do with unsent packets in the tx_buffer.
>>
>
> Just to summarise why I think it is better to have tx buffering managed on the app level:
>
> 1. avoid any ABI change.
> 2. Avoid extra changes in rte_ethdev.c: tx_queue_setup/tx_queue_stop.
> 3. Provides much more flexibility to the user:
> a) where to allocate space for tx_buffer (stack, heap, hugepages, etc).
> b) user can mix and match plain tx_burst() and tx_buffer/tx_buffer_flush()
> in any way he fills it appropriate.
> c) user can change the size of tx_buffer without stop/re-config/start queue:
> just allocate new larger(smaller) tx_buffer & copy contents to the new one.
> d) user can preserve buffered packets through device restart circle:
> i.e if let say TX hang happened, and user has to do dev_stop/dev_start -
> contents of tx_buffer will stay unchanged and its contents could be
> (re-)transmitted after device is up again, or through different port/queue if needed.
>
> As a drawbacks mentioned - tx error handling becomes less transparent...
> But we can add error handling routine and it's user provided parameter
> into struct rte_eth_dev_tx_buffer', something like that:
>
> +struct rte_eth_dev_tx_buffer {
> + buffer_tx_error_fn cbfn;
> + void *userdata;
> + unsigned nb_pkts;
> + uint64_t errors;
> + /**< Total number of queue packets to sent that are dropped. */
> + struct rte_mbuf *pkts[];
> +};
>
> Konstantin
>
Just to enforce Konstantin's comments.
As a very basic - not to say fundamental - rule, one should avoid adding
in the PMD RX/TX API any extra processing that can be handled at a
higher level.
The only and self-sufficient reason is that we must avoid impacting
performances on the critical path, in particular for those - usually the
majority of - applications that do not need such extra operations, or
better implement them at upper level.
Maybe in a not so far future will come a proposal for forking a new open
source fast-dpdk project aiming at providing API simplicity,
zero-overhead, modular design, and all those nice properties that every
one claims to seek :-)
Ivan
next prev parent reply other threads:[~2016-02-12 16:40 UTC|newest]
Thread overview: 44+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-01-15 14:43 [dpdk-dev] [PATCH 0/2] add support for buffered tx to ethdev Tomasz Kulasek
2016-01-15 14:43 ` [dpdk-dev] [PATCH 1/2] ethdev: add buffered tx api Tomasz Kulasek
2016-01-15 18:13 ` Stephen Hemminger
2016-01-15 18:14 ` Stephen Hemminger
2016-01-15 18:44 ` Ananyev, Konstantin
2016-02-02 10:00 ` Kulasek, TomaszX
2016-02-02 13:49 ` Ananyev, Konstantin
2016-02-09 17:02 ` Kulasek, TomaszX
2016-02-09 23:56 ` Ananyev, Konstantin
2016-02-12 11:44 ` Ananyev, Konstantin
2016-02-12 16:40 ` Ivan Boule [this message]
2016-02-12 17:33 ` Bruce Richardson
2016-01-15 14:43 ` [dpdk-dev] [PATCH 2/2] examples: sample apps rework to use " Tomasz Kulasek
2016-01-15 18:12 ` [dpdk-dev] [PATCH 0/2] add support for buffered tx to ethdev Stephen Hemminger
2016-02-24 17:08 ` [dpdk-dev] [PATCH v2 " Tomasz Kulasek
2016-02-24 17:08 ` [dpdk-dev] [PATCH v2 1/2] ethdev: add buffered tx api Tomasz Kulasek
2016-03-08 22:52 ` Thomas Monjalon
2016-03-09 13:36 ` Ananyev, Konstantin
2016-03-09 14:25 ` Thomas Monjalon
2016-03-09 15:23 ` Ananyev, Konstantin
2016-03-09 15:26 ` Thomas Monjalon
2016-03-09 15:32 ` Kulasek, TomaszX
2016-03-09 15:37 ` Thomas Monjalon
2016-03-09 15:42 ` Ananyev, Konstantin
2016-03-09 15:52 ` Thomas Monjalon
2016-03-09 16:17 ` Ananyev, Konstantin
2016-03-09 16:21 ` Thomas Monjalon
2016-03-09 16:35 ` Kulasek, TomaszX
2016-03-09 17:06 ` Thomas Monjalon
2016-03-09 18:12 ` Kulasek, TomaszX
2016-02-24 17:08 ` [dpdk-dev] [PATCH v2 2/2] examples: rework to use " Tomasz Kulasek
2016-02-25 16:17 ` [dpdk-dev] [PATCH v2 0/2] add support for buffered tx to ethdev Ananyev, Konstantin
2016-03-10 10:57 ` [dpdk-dev] [PATCH v3 " Tomasz Kulasek
2016-03-10 10:57 ` [dpdk-dev] [PATCH v3 1/2] ethdev: add buffered tx api Tomasz Kulasek
2016-03-10 16:23 ` Thomas Monjalon
2016-03-10 17:15 ` Kulasek, TomaszX
2016-03-10 10:57 ` [dpdk-dev] [PATCH v3 2/2] examples: rework to use buffered tx Tomasz Kulasek
2016-03-10 11:31 ` [dpdk-dev] [PATCH v3 0/2] add support for buffered tx to ethdev Ananyev, Konstantin
2016-03-10 16:01 ` Jastrzebski, MichalX K
2016-03-10 17:19 ` [dpdk-dev] [PATCH v4 " Tomasz Kulasek
2016-03-10 17:19 ` [dpdk-dev] [PATCH v4 1/2] ethdev: add buffered tx api Tomasz Kulasek
2016-03-10 17:19 ` [dpdk-dev] [PATCH v4 2/2] examples: rework to use buffered tx Tomasz Kulasek
2016-03-11 16:39 ` [dpdk-dev] [PATCH v4 0/2] add support for buffered tx to ethdev Thomas Monjalon
-- strict thread matches above, loose matches on Subject: below --
2016-01-15 14:26 [dpdk-dev] [PATCH 1/2] ethdev: add buffered tx api Tomasz Kulasek
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