From: Shreyansh Jain <shreyansh.jain@nxp.com>
To: "Ananyev, Konstantin" <konstantin.ananyev@intel.com>,
Matan Azrad <matan@mellanox.com>,
Nikhil Agarwal <nikhil.agarwal@linaro.org>
Cc: "dev@dpdk.org" <dev@dpdk.org>,
"Hunt, David" <david.hunt@intel.com>,
"nikhil.agarwal@nxp.com" <nikhil.agarwal@nxp.com>,
"hemant.agrawal@nxp.com" <hemant.agrawal@nxp.com>,
"Yigit, Ferruh" <ferruh.yigit@intel.com>
Subject: Re: [dpdk-dev] [PATCH 1/3] ethdev: add max burst size to device info
Date: Wed, 13 Dec 2017 20:52:26 +0530 [thread overview]
Message-ID: <51033c92-d286-6785-62c1-a9797046422c@nxp.com> (raw)
In-Reply-To: <2601191342CEEE43887BDE71AB9772585FAC91DE@irsmsx105.ger.corp.intel.com>
On Wednesday 13 December 2017 06:22 PM, Ananyev, Konstantin wrote:
>
>
>> -----Original Message-----
>> From: Shreyansh Jain [mailto:shreyansh.jain@nxp.com]
>> Sent: Tuesday, December 12, 2017 1:44 PM
>> To: Ananyev, Konstantin <konstantin.ananyev@intel.com>; Matan Azrad <matan@mellanox.com>; Nikhil Agarwal
>> <nikhil.agarwal@linaro.org>
>> Cc: dev@dpdk.org; Hunt, David <david.hunt@intel.com>; nikhil.agarwal@nxp.com; hemant.agrawal@nxp.com; Yigit, Ferruh
>> <ferruh.yigit@intel.com>
>> Subject: Re: [PATCH 1/3] ethdev: add max burst size to device info
>>
[...]
>>>> Doesn't such like devices PMDs should try to retrieve multiple HW burst to adjust the asked received packet number?
>>>
>>> Same thought here...
>>> Can't that limitation be hidden inside PMD by calling HW burst multiple times?
>>
>> This might be required in some cases for performance.
>> It is possible that for each request containing N buffers, if the PMD
>> fetches all N (more than its preferred burst_size), cache misses reduce
>> the performance - especially for SoC with limited cache size.
>>
>> Also, a complete cycle of
>> application->driver->hardware->driver->application can help driver
>> prefetch buffers - which, in case of hw burst looping, might be too
>> little to complete the prefetch cycle.
>>
>> To summarize, indeed this is for performance specific cases and the idea
>> that @Matan gave for renaming 'perf_buf_size' to highlight this, sounds
>> logical.
>>
>>> Also if I am not mistaken - it would increase size of struct rte_eth_dev_info, right?
>>> If so, then it means ABI breakage.
>>
>> Yes, deprecation notice should have been sent - if we continue with the
>> dev_info change. To me that looks as one of the option. Maybe, someone
>> on the list has a better idea.
>
> In theory there is at least 2 free bytes at the end of struct rte_eth_desc_lim.
> Might be it would help a bit.
:) Thanks for highlighting.
So, you feel it is OK to reuse this assumption of hole in alignment? It
certainly would bypass the ABI limitation but not sure which cases it
would break (for example, same assumptions by others)
It would an issue in case of 32bit systems, though.
[...]
-
Shreyansh
next prev parent reply other threads:[~2017-12-13 15:08 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-12-12 10:05 Nikhil Agarwal
2017-12-12 10:05 ` [dpdk-dev] [PATCH 2/3] net/dpaa: implement max burst size in dev info Nikhil Agarwal
2017-12-12 10:05 ` [dpdk-dev] [PATCH 3/3] examples/l3fwd-power: use device max burst size Nikhil Agarwal
2017-12-12 10:45 ` [dpdk-dev] [PATCH 1/3] ethdev: add max burst size to device info Matan Azrad
2017-12-12 11:03 ` Ananyev, Konstantin
2017-12-12 13:43 ` Shreyansh Jain
2017-12-13 12:52 ` Ananyev, Konstantin
2017-12-13 15:22 ` Shreyansh Jain [this message]
2018-05-22 22:17 ` Thomas Monjalon
2019-04-05 14:55 ` Ferruh Yigit
2019-04-05 14:55 ` Ferruh Yigit
2019-04-05 14:57 ` Yigit, Ferruh
2019-04-05 14:57 ` Yigit, Ferruh
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