From: "De Lara Guarch, Pablo" <pablo.de.lara.guarch@intel.com>
To: Thomas Monjalon <thomas@monjalon.net>,
"Dumitrescu, Cristian" <cristian.dumitrescu@intel.com>
Cc: "dev@dpdk.org" <dev@dpdk.org>, Jianbo Liu <jianbo.liu@linaro.org>,
"jerin.jacob@caviumnetworks.com" <jerin.jacob@caviumnetworks.com>,
"ashwin.sekhar@caviumnetworks.com"
<ashwin.sekhar@caviumnetworks.com>
Subject: Re: [dpdk-dev] [PATCH] examples/ip_pipeline: use crc32 in hash functions for arm64
Date: Tue, 4 Jul 2017 13:55:01 +0000 [thread overview]
Message-ID: <E115CCD9D858EF4F90C690B0DCB4D8976CBD5529@IRSMSX108.ger.corp.intel.com> (raw)
In-Reply-To: <1851401.bCM4vaXCYT@xps>
> -----Original Message-----
> From: Thomas Monjalon [mailto:thomas@monjalon.net]
> Sent: Tuesday, July 4, 2017 12:26 AM
> To: Dumitrescu, Cristian <cristian.dumitrescu@intel.com>; De Lara Guarch,
> Pablo <pablo.de.lara.guarch@intel.com>
> Cc: dev@dpdk.org; Jianbo Liu <jianbo.liu@linaro.org>;
> jerin.jacob@caviumnetworks.com; ashwin.sekhar@caviumnetworks.com
> Subject: Re: [dpdk-dev] [PATCH] examples/ip_pipeline: use crc32 in hash
> functions for arm64
>
> 04/07/2017 01:19, Dumitrescu, Cristian:
> > From: Thomas Monjalon [mailto:thomas@monjalon.net]
> > > 18/05/2017 11:09, Jianbo Liu:
> > > > Implement the same hash functions with crc32 on arm platform.
> > > >
> > > > Signed-off-by: Jianbo Liu <jianbo.liu@linaro.org>
> > > > ---
> > > > examples/ip_pipeline/pipeline/hash_func.h | 2 +
> > > > examples/ip_pipeline/pipeline/hash_func_arm64.h | 245
> > > ++++++++++++++++++++++++
> > > > 2 files changed, 247 insertions(+) create mode 100644
> > > > examples/ip_pipeline/pipeline/hash_func_arm64.h
> > >
> > > I don't understand why this code is in an example.
> > > We have some CRC code in librte_hash, librte_net and ip_pipeline.
> > > Cristian, Jianbo,
> > > does it make sense to move these functions somewhere else?
> > >
> >
> > I think example apps are a great way to propose new hash functions.
> > IMO we should encourage the definition/exploration of new hash
> functions in our example apps.
> >
> > These functions are examples of how fast hash functions can be built
> using special CPU instructions.
> > They have much better performance than e.g. jhash, but their
> > properties are largely unknown, as no rigorous study on their
> > properties (such as uniform distribution) has been conducted. I have
> > seen them providing good performance for the data set I have been
> using, but I have no extensive data to support their maturity level.
> >
> > If somebody is willing to invest the effort in proving them, I would
> > be more than happy to see them moved to a library like librte_hash.
> > Pablo as maintainer has the choice (I think it is not the first time
> > we discuss bout these hash funcs :) )
> >
> > As mentioned in one of our deprecation notices, I am actively working
> > (not ready for 17.8 unfortunately) to add a key mask parameter to these
> functions, so more work on these hash functions is likely to take place.
>
> OK thanks for the explanation.
> I still think we do not need to prove hash for integrating them.
> I would be interested to read Pablo's opinion.
If these functions are used as hash functions, I would place them in rte_hash.
The case where we placed the CRC function in librte_net was because that
was not used as a hash function, so it made sense to me placing it there,
but in this case, it looks like it is, so I think rte_hash is a valid place
(although someone would need to integrate it with the existing CRC hash function in that library).
Thanks,
Pablo
next prev parent reply other threads:[~2017-07-04 13:56 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-05-18 9:09 Jianbo Liu
2017-07-03 21:11 ` Thomas Monjalon
2017-07-03 23:19 ` Dumitrescu, Cristian
2017-07-03 23:25 ` Thomas Monjalon
2017-07-04 13:55 ` De Lara Guarch, Pablo [this message]
2017-07-05 3:38 ` Jianbo Liu
2017-10-24 15:38 ` Dumitrescu, Cristian
2017-10-25 7:01 ` Jianbo Liu
2017-10-27 9:25 ` [dpdk-dev] [PATCH v2] " Jianbo Liu
2017-10-27 9:55 ` Dumitrescu, Cristian
2017-11-07 7:51 ` Ferruh Yigit
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