From: Vamsi Krishna Attunuru <vattunuru@marvell.com>
To: Ferruh Yigit <ferruh.yigit@intel.com>, "dev@dpdk.org" <dev@dpdk.org>
Cc: "arybchenko@solarflare.com" <arybchenko@solarflare.com>,
"Jerin Jacob Kollanukkaran" <jerinj@marvell.com>,
"thomas@monjalon.net" <thomas@monjalon.net>
Subject: Re: [dpdk-dev] [PATCH v2 1/3] lib/ethdev: add ethdev op to get hash index
Date: Tue, 15 Oct 2019 17:28:06 +0000 [thread overview]
Message-ID: <MWHPR18MB164582B0ED39A2E526FA3EA9A6930@MWHPR18MB1645.namprd18.prod.outlook.com> (raw)
In-Reply-To: <36841a25-b5c8-ad4c-9fee-16ad8e0270ff@intel.com>
> -----Original Message-----
> From: dev <dev-bounces@dpdk.org> On Behalf Of Ferruh Yigit
> Sent: Tuesday, October 15, 2019 10:17 PM
> To: Vamsi Krishna Attunuru <vattunuru@marvell.com>; dev@dpdk.org
> Cc: arybchenko@solarflare.com; Jerin Jacob Kollanukkaran
> <jerinj@marvell.com>; thomas@monjalon.net
> Subject: Re: [dpdk-dev] [PATCH v2 1/3] lib/ethdev: add ethdev op to get hash
> index
>
> On 10/15/2019 10:52 AM, vattunuru@marvell.com wrote:
> > From: Vamsi Attunuru <vattunuru@marvell.com>
> >
> > Some networking devices may use custom algos for computing hash
> > indices and spread the packets accordingly.
> >
> > Patch adds an eth_dev op to get the hash index correspond to the given
> > hash value received in the initial packet on the given port.
> >
> > Some of the applications compute hash index from the hash value
> > received in the initial packet and than configure the rxq to lcore
> > mapping to make sure the mapped lcore/rxq would receive the upcoming
> > traffic that has similar hash.
> > Such applications may use these API to get the hash index used by the
> > PMD for spreading those traffic.
>
> Hi Vamsi,
>
> Can you please describe this usecase?
> If the application is receiving the packet, it already knows which queue it is
> coming from, what is the benefit of the getting hash index?
Hi Ferruh,
I think the commit msg is incomplete and did not explain the use case clearly, my apologies.
Actual usecase is when application precalculates the hash value using some hashlib for a specific type of packet headers with the same hash key that's configured in the HW, application would compute hash_index as hash % reta_size and predict the packets on the computed queue index. But these hash_index computation might be different from PMD/HW computed index(based it's algo design). To fix those disparity, these API been introduced which can be used during configuration time to have
required lcore-rq mapping.
>
> The concern is adding a new API which is specific to a use case and HW and
> won't be used in long term. That will only create technical dept for us.
>
> >
> > Signed-off-by: Vamsi Attunuru <vattunuru@marvell.com>
>
> <...>
next prev parent reply other threads:[~2019-10-15 17:28 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-14 5:52 [dpdk-dev] [PATCH v1 0/3] " vattunuru
2019-09-14 5:52 ` [dpdk-dev] [PATCH v1 1/3] lib/ethdev: " vattunuru
2019-10-03 13:00 ` Andrew Rybchenko
2019-10-07 4:45 ` [dpdk-dev] [EXT] " Vamsi Krishna Attunuru
2019-10-15 9:52 ` [dpdk-dev] [PATCH v2 0/3] " vattunuru
2019-10-15 9:52 ` [dpdk-dev] [PATCH v2 1/3] lib/ethdev: " vattunuru
2019-10-15 16:47 ` Ferruh Yigit
2019-10-15 17:28 ` Vamsi Krishna Attunuru [this message]
2019-10-16 17:47 ` Ferruh Yigit
2019-10-16 17:48 ` Ferruh Yigit
2019-10-15 9:52 ` [dpdk-dev] [PATCH v2 2/3] app/test: add hash index verify autotest vattunuru
2019-10-15 16:49 ` Ferruh Yigit
2019-10-15 9:52 ` [dpdk-dev] [PATCH v2 3/3] net/octeontx2: add eth dev op callback to get hash index vattunuru
2019-09-14 5:52 ` [dpdk-dev] [PATCH v1 2/3] app/test: add hash index verify autotest vattunuru
2019-09-14 5:52 ` [dpdk-dev] [PATCH v1 3/3] net/octeontx2: add eth dev op callback to get hash index vattunuru
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