Hi Olivier,
On Tuesday 04 July 2017 09:29 PM, Olivier Matz wrote:
> Hi Santosh,
>
> On Tue, 4 Jul 2017 17:55:54 +0530, santosh
> <santosh.shu...@caviumnetworks.com> wrote:
>> Hi Olivier,
>>
>> On Friday 30 June 2017 07:42 PM, Olivier Matz wrote:
>>
>>> Hi,
>>>
>>> On Tue, 20 Jun 2017 19:34:15 +0530, Jerin Jacob
>>> <jerin.ja...@caviumnetworks.com> wrote:
>>>> -----Original Message-----
>>>>> Date: Tue, 20 Jun 2017 16:07:17 +0530
>>>>> From: Hemant Agrawal <hemant.agra...@nxp.com>
>>>>> To: Jerin Jacob <jerin.ja...@caviumnetworks.com>
>>>>> CC: Santosh Shukla <santosh.shu...@caviumnetworks.com>,
>>>>> olivier.m...@6wind.com, dev@dpdk.org
>>>>> Subject: Re: [PATCH 0/2] Allow application set mempool handle
>>>>> User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:45.0) Gecko/20100101
>>>>> Thunderbird/45.8.0
>>>>>
>>>>> On 6/19/2017 6:31 PM, Jerin Jacob wrote:
>>>>>> -----Original Message-----
>>>>>>> Date: Mon, 19 Jun 2017 17:22:46 +0530
>>>>>>> From: Hemant Agrawal <hemant.agra...@nxp.com>
>>>>>>> To: Santosh Shukla <santosh.shu...@caviumnetworks.com>,
>>>>>>> olivier.m...@6wind.com, dev@dpdk.org
>>>>>>> CC: jerin.ja...@caviumnetworks.com
>>>>>>> Subject: Re: [PATCH 0/2] Allow application set mempool handle
>>>>>>> User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:45.0) Gecko/20100101
>>>>>>> Thunderbird/45.8.0
>>>>>>>
>>>>>>> On 6/1/2017 1:35 PM, Santosh Shukla wrote:
>>>>>>>> Some platform can have two different NICs for example external PCI
>>>>>>>> Intel
>>>>>>>> 40G card and Integrated NIC like vNIC/octeontx/dpaa2.
>>>>>>>>
>>>>>>>> Both NICs like to use their preferred pool e.g. external PCI card/
>>>>>>>> vNIC's
>>>>>>>> preferred pool would be the ring based pool and octeontx/dpaa2
>>>>>>>> preferred would
>>>>>>>> be ext-mempools.
>>>>>>>> Right now, Framework doesn't support such case. Only one pool can be
>>>>>>>> used across two different NIC's. For that, user has to statically set
>>>>>>>> CONFIG_RTE_MEMPOOL_DEFAULT_OPS=<pool-name>.
>>>>>>>>
>>>>>>>> So proposing two approaches:
>>>>>>>> Patch 1) Introducing eal option --pkt-mempool=<pool-name>
>>>>>>>> Patch 2) Introducing ethdev API called _get_preferred_pool(), where
>>>>>>>> PMD driver
>>>>>>>> gets a chance to advertise their pool capability to the application.
>>>>>>>> And based
>>>>>>>> on that hint- application creates pools for that driver.
>>>>> If the system is having more than one heterogeneous ethernet device with
>>>>> different mempool, the application has to create different mempool for
>>>>> each
>>>>> of the ethernet device.
>>>>>
>>>>> However, let's take a case
>>>>> As system has a DPAA2 eth device, which only work with dpaa2 mempools.
>>>> dpaa2 ethdev will return dpaa2 mempool as preferred handler.
>>>>
>>>>> System also detect a standard PCI NIC, which can work with any software
>>>>> mempool (e.g ring_mp_mc) or with dpaa2 mempool. Given the preference, PCI
>>>>> NIC will have preferred as software mempool.
>>>>> how the application will choose between these, if it want to create only
>>>>> one
>>>>> mempool?
>>>> We need add some policy in common code to help application to choose
>>>> in case if application interested in creating in one pool for
>>>> heterogeneous cases. It is more of application problem, ethdev can
>>>> return the preferred handler, let application choose interested in one.
>>>> ethdev is depended on the specific mempool not any other object.
>>>>
>>>> We will provide option 1(eal argument based one) as one policy.More
>>>> sophisticated
>>>> policies we need add in application.
>>>>
>>>>
>>>>> Or, how the scheme will work if the application want to create only one
>>>>> mempool?
>>>> option 1 (eal argument based) or we need to change the application to
>>>> choose from available ethdev count and its preferred mempool handler.
>>> I also think the approach in this patchset is not that bad:
>>>
>>> - The first step is to allow the user to specify the mempool
>>> dynamically (eal arg).
>>>
>>> One thing I don't really like is to have a mempool-related argument
>>> inside eal. It would be better if eal could provide a framework so
>>> that each libraries (ex: mbuf, mempool) can register their argument
>>> that could be changed through the command line or trough an API.
>>>
>>> Without this, it introduces a sort of dependency between eal and
>>> mempool, which I don't think is sane.
>> Yes, eal has no such framework for the non-eal library.
>>
>> IIUC, then are you looking at something like below:
>> - All non-eal library to register their callback function with eal.
>> - EAL iterates through registered callbacks and calls them one by one.
>> - EAL don't do the parsing and those non-eal libs do the parsing.
>> - EAL passes char *string arg as input to those registered callback function.
>> - It is up to those callback function to parse and find out i/p arg is
>> correct
>> or incorrect.
>> - Having said that, then in the mempool case; We need to add new API to list
>> the number of supported mempool handles(by name) and then compare/match
>> i/p string with mempool handle(byname).
>>
>> Are you referring to such framework? did I catch everything alright?
> Here is how I see this feature (very high level).
> The first step would be quite simple (no registration).
> The EAL manages a key value database, and provides a key/value API like this:
>
> /* return NULL if key is not in database */
> const char *rte_eal_cfg_get(const char *key);
> /* value can be NULL to delete the key, return 0 on success */
> int rte_eal_cfg_set(const char *key, const char *value);
>
> At startup, the EAL parses the arguments like this:
> --cfg=key:value
> Example:
> --cfg=mbuf.default_pool:ring
>
> Another way to set these options could be a config file (maybe the
> librte_cfgfile could be useful for that, I don't know). Probably
> something like:
> --cfgfile=file.conf
>
> The EAL parsing layer calls rte_eal_cfg_set()
>
> Then, a library like librte_mbuf can query a specific key
> through rte_eal_cfg_get("mbuf.default_pool"). No registration would
> be needed. We'd need to define a convention for the key names.
>
> It could be extented in a second step by adding a registration in
> the constructor of the library:
> /* check_cb is a function that is called to check if the parsing is
> * correct. Maybe an opaque arg could be added too. */
> rte_eal_register_cfg(const char *key, rte_eal_cfg_check_cb_t check_cb);
>
>
> I'm sure many people will have an opinion on this topic, which could
> be different than mine.
>
Thanks for approach. But I think we should take up as separate topic.
>>> - The second step is to be able to ask to the eth devices which
>>> mempool they prefer. If there is only one kind of port, it's
>>> quite easy.
>>>
>>> As suggested, more complexity could go in the application if
>>> required, or some helpers could be provided in the future.
>>>
>>>
>>> I'm sending some comments as replies to the patches.
>>>
>> If above eal framework approach is meeting your expectation then [1/4] need
>> rework?
>> Or you want to keep [1/4] patch and I'll send v2 patch incorporating
>> your inline review comment, which one you prefer?
> Adding a specific EAL argument --pkt-mempool could do the job for now.
> But I'd be happy to see someone working on a generic cfg framework in EAL,
> which seems to be a longer term solution, and helpful for other libs.
>
> Some parts of EAL have currently no maintainer, which is a problem
> to get a good feedback. But I guess a proposition on this topic
> would trigger many comments.
>
I may take up this (per my BW), but for now I prefer to follow --pkt-mempool
approach. I guess, --pkt-mempool will address heterogeneous pool-handle
use-case.
so Its priority (imo).
Thanks for feedback Olivier.
> Regards,
> Olivier
