From: "Morten Brørup" <mb@smartsharesystems.com>
To: "Yang, Zhiyong" <zhiyong.yang@intel.com>,
"Wiles, Keith" <keith.wiles@intel.com>
Cc: "Thomas Monjalon" <thomas@monjalon.net>, DPDK <dev@dpdk.org>,
"Olivier Matz" <olivier.matz@6wind.com>,
"Wang, Zhihong" <zhihong.wang@intel.com>,
"Yuanhan Liu" <yuanhan.liu@linux.intel.com>,
"Ananyev, Konstantin" <konstantin.ananyev@intel.com>,
"Richardson, Bruce" <bruce.richardson@intel.com>,
"Chilikin, Andrey" <andrey.chilikin@intel.com>,
"Jan Blunck" <jblunck@infradead.org>,
"Nélio Laranjeiro" <nelio.laranjeiro@6wind.com>,
arybchenko@solarflare.com, jerin.jacob@caviumnetworks.com
Subject: Re: [dpdk-dev] [PATCH v2 6/8] mbuf: use 2 bytes for port andnbsegments
Date: Wed, 12 Jul 2017 11:50:38 +0200 [thread overview]
Message-ID: <98CBD80474FA8B44BF855DF32C47DC359EB28F@smartserver.smartshare.dk> (raw)
In-Reply-To: <E182254E98A5DA4EB1E657AC7CB9BD2A6591FB78@BGSMSX101.gar.corp.intel.com>
> -----Original Message-----
> From: Yang, Zhiyong [mailto:zhiyong.yang@intel.com]
> Sent: Wednesday, July 12, 2017 11:02 AM
> To: Morten Brørup; Wiles, Keith
> Cc: Thomas Monjalon; DPDK; Olivier Matz; Wang, Zhihong; Yuanhan Liu;
> Ananyev, Konstantin; Richardson, Bruce; Chilikin, Andrey; Jan Blunck;
> Nélio Laranjeiro; arybchenko@solarflare.com;
> jerin.jacob@caviumnetworks.com
> Subject: RE: [dpdk-dev] [PATCH v2 6/8] mbuf: use 2 bytes for port
> andnbsegments
>
>
>
> > -----Original Message-----
> > From: dev [mailto:dev-bounces@dpdk.org] On Behalf Of Morten Brørup
> > Sent: Wednesday, July 12, 2017 3:25 PM
> > To: Wiles, Keith <keith.wiles@intel.com>
> > Cc: Thomas Monjalon <thomas@monjalon.net>; DPDK <dev@dpdk.org>;
> > Olivier Matz <olivier.matz@6wind.com>; Wang, Zhihong
> > <zhihong.wang@intel.com>; Yuanhan Liu <yuanhan.liu@linux.intel.com>;
> > Ananyev, Konstantin <konstantin.ananyev@intel.com>; Richardson, Bruce
> > <bruce.richardson@intel.com>; Chilikin, Andrey
> > <andrey.chilikin@intel.com>; Jan Blunck <jblunck@infradead.org>;
> Nélio
> > Laranjeiro <nelio.laranjeiro@6wind.com>; arybchenko@solarflare.com;
> > jerin.jacob@caviumnetworks.com
> > Subject: Re: [dpdk-dev] [PATCH v2 6/8] mbuf: use 2 bytes for port and
> > nbsegments
> >
> > > -----Original Message-----
> > > From: dev [mailto:dev-bounces@dpdk.org] On Behalf Of Wiles, Keith
> > > Sent: Tuesday, July 11, 2017 6:48 PM
> > > To: Morten Brørup
> > > Cc: Thomas Monjalon; DPDK; Olivier Matz; Wang, Zhihong; Yuanhan
> Liu;
> > > Ananyev, Konstantin; Richardson, Bruce; Chilikin, Andrey; Jan
> > > Blunck; Nélio Laranjeiro; arybchenko@solarflare.com;
> > > jerin.jacob@caviumnetworks.com
> > > Subject: Re: [dpdk-dev] [PATCH v2 6/8] mbuf: use 2 bytes for port
> > > and nbsegments
> > >
> > >
> > > > On Jul 11, 2017, at 10:23 AM, Morten Brørup
> > > <mb@smartsharesystems.com> wrote:
> > > >
> > > >> -----Original Message-----
> > > >> From: dev [mailto:dev-bounces@dpdk.org] On Behalf Of Thomas
> > > >> Monjalon
> > > >> Sent: Tuesday, July 11, 2017 5:06 PM
> > > >> To: Morten Brørup
> > > >> Cc: dev@dpdk.org; Wiles, Keith; Olivier Matz; Wang, Zhihong;
> > > >> Yuanhan Liu; Ananyev, Konstantin; Richardson, Bruce; Chilikin,
> > > >> Andrey; Jan Blunck; nelio.laranjeiro@6wind.com;
> > > >> arybchenko@solarflare.com; jerin.jacob@caviumnetworks.com
> > > >> Subject: Re: [dpdk-dev] [PATCH v2 6/8] mbuf: use 2 bytes for
> port
> > > and
> > > >> nbsegments
> > > >>
> > > >> 11/07/2017 15:30, Morten Brørup:
> > > >>> Morten Brørup wrote:
> > > >>>> Olivier Matz wrote:
> > > >>>>> As I said in a previous message, I think a good first step
> > > >>>>> would be to introduce a typedef for the port number:
> > > >> rte_eth_port_num_t.
> > > >>>>> It can still be uint8_t for now, and can be switched to 16
> > > >>>>> bits
> > > >> in
> > > >>>>> one step when everyone uses this new type.
> > > >>>>
> > > >>>> I think that DPDK follows the Linux tradition of exposing the
> > > >>>> variable types, as opposed to hiding them behind typedefs.
> This
> > > has
> > > >>>> the unfortunate consequence that when a variable type changes,
> > > >>>> it has to be changed everywhere.
> > > >>>>
> > > >>>> Introducing a rte_eth_port_num_t will require changing the
> same
> > > >>>> files at the same locations everywhere, so not even as a
> > > >>>> temporary solution will it be beneficial.
> > > >> [...]
> > > >>> What I was trying to communicate with my long argument about
> > > >>> type
> > > >> definitions was: When the type changed from 8 bit to 16 bit, the
> > > type
> > > >> needs to change from uint8_t to uint16_t everywhere too,
> > > >> including
> > > in
> > > >> the ethdev APIs.
> > > >>>
> > > >>> Don't start breaking coding conventions here by hiding the type
> > > >>> of
> > > >> this variable.
> > > >>
> > > >> So, Morten, you are against the typedef, right?
> > > >> Because we need to change it everywhere anyway, right?
> > > >>
> > > >> Note: I have no strong opinion.
> > > >
> > > > I'm against the typedef because it would break convention, and
> I'm
> > > > a
> > > strong proponent of conventions. In other projects, I'm all for
> > > typedefs, virtual classes, inheritance etc., but DPDK follows the
> > > Linux convention of not hiding simple types.
> > > >
> > > > We need to change it from uint8_t everywhere, regardless what we
> > > > change it to. (But if we need to change it again sometime in the
> > > > future, then a typedef will save us next time.)
> > >
> > > If the number of ports go beyond 64K then I will be the first one
> > > (if still alive) to eat this email. :-) The only reason to have
> more
> > > then
> > > 2 bytes would be to encode something into the port id value, which
> I
> > > could see, but a very slim chance IMHO.
> > >
> > > >
> > > > However, if we change the convention and start hiding simple
> > > > types,
> > > they still need the rte_ prefix regardless if they are popular or
> > > obscure types. Even struct rte_mbuf has the rte_ prefix, and I
> > > consider that a very popular type. If so, rte_port_t would be a
> good
> > > name for this type.
> > > >
> > > > My preference: Follow convention and change it to uint16_t
> > > everywhere.
> > > >
> > > > Med venlig hilsen / kind regards
> > > > - Morten Brørup
> > > >
> > >
> > > As we must change the uint8_t to uint16_t, then I would like it to
> > > be more descriptive via a typedef. I really do not see us needing
> to
> > > change it again in the near future. The only reason to make it a
> > > typedef is to be able to identify from just the prototype of the
> > > function that it takes a port ID value, which I am in favor of
> doing
> > > here for that reason.
> >
> > That is not a very good reason: When used as a function parameter,
> the
> > type is only shown in the function declaration, whereas the variable
> > name is shown every time it is used inside the function. So remember
> > to always use meaningful variable names, such as "port" (like in the
> > mbuf structure) or "port_id" (used in other places).
> >
> > >
> > > As for Olivier’s statement about the typedef name I do not see the
> > > need for ‘_eth_' to be part of the typedef as it conveys no extra
> > > information in the name. Everything port related in DPDK is a
> > > ethernet type device or port. If we do add something like fiber
> > > channel maybe rte_pid_t is reason to that too, but if it contains
> > > ‘_eth_’ it would not.
> > >
> > > I would like to see names that are just short enough to convey the
> > > information and not be redundant. IMHO rte_pid_t is fine, but if we
> > > use some something similar to the length of uint8_t (7) or uint16_t
> > > (8) characters then we would not have to also reformat the line
> more
> > > then needed. Using rte_pid_t (pid == port_id) we only extend the
> > > length by one (or two) characters and most likely the added byte(s)
> > > will not cause more format problems in the code.
> >
> > I still don't support typedefs for scalar types. I consider it
> against
> > the coding style, although after reviewing the official DPDK Coding
> > Style documentation
> > (http://dpdk.org/doc/guides/contributing/coding_style.html), I can
> see
> > that it is not explicitly stated. Please also note that section 1.5.7
> > of the DPDK Coding Style documentation says that the _t postfix
> should
> > be avoided. Anyway, if we end up with a typedef, please don't use
> > something resembling pid_t known from POSIX
> > (https://www.gnu.org/software/libc/manual/html_node/Process-
> > Identification.html).
> >
>
> How about rte_dev_id_t?
>
> Thanks
> Zhiyong
>
> >
> > >
> > > Regards,
> > > Keith
If the DPDK Coding Style is based on Linux Coding Style, we should avoid typedefs in general, not just for structures. Please read Linus Torvalds' opinions about it: http://yarchive.net/comp/linux/typedefs.html
Perhaps the DPDK Coding Style should be updated to clarify this. (Or if we decide otherwise, to explicitly mention this deviation from the Linux coding style.)
Med venlig hilsen / kind regards
- Morten Brørup
next prev parent reply other threads:[~2017-07-12 9:50 UTC|newest]
Thread overview: 155+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-01-24 15:19 [dpdk-dev] [RFC 0/8] mbuf: structure reorganization Olivier Matz
2017-01-24 15:19 ` [dpdk-dev] [RFC 1/8] mbuf: make segment prefree function public Olivier Matz
2017-01-24 15:19 ` [dpdk-dev] [RFC 2/8] mbuf: make raw free " Olivier Matz
2017-01-24 15:19 ` [dpdk-dev] [RFC 3/8] mbuf: set mbuf fields while in pool Olivier Matz
2017-01-24 15:50 ` Bruce Richardson
2017-02-28 14:51 ` Olivier Matz
2017-01-24 15:19 ` [dpdk-dev] [RFC 4/8] net: don't touch mbuf next or nb segs on Rx Olivier Matz
2017-01-24 15:19 ` [dpdk-dev] [RFC 5/8] mbuf: make rearm data address naturally aligned Olivier Matz
2017-01-24 15:19 ` [dpdk-dev] [RFC 6/8] mbuf: use 2 bytes for port and nb segments Olivier Matz
2017-01-24 15:19 ` [dpdk-dev] [RFC 7/8] mbuf: move sequence number in second cache line Olivier Matz
2017-01-24 15:19 ` [dpdk-dev] [RFC 8/8] mbuf: add a timestamp field Olivier Matz
2017-01-24 15:59 ` [dpdk-dev] [RFC 0/8] mbuf: structure reorganization Bruce Richardson
2017-01-24 16:16 ` Olivier MATZ
2017-02-06 18:41 ` Ananyev, Konstantin
2017-02-09 16:20 ` Morten Brørup
2017-02-09 16:56 ` Ananyev, Konstantin
2017-02-16 13:48 ` Olivier Matz
2017-02-16 15:46 ` Bruce Richardson
2017-02-16 16:14 ` Olivier Matz
2017-02-21 14:20 ` Morten Brørup
2017-02-21 14:28 ` Bruce Richardson
2017-02-21 15:04 ` Olivier MATZ
2017-02-21 15:18 ` Bruce Richardson
2017-02-21 15:18 ` Morten Brørup
2017-02-19 19:04 ` Chilikin, Andrey
2017-02-21 9:53 ` Olivier MATZ
2017-02-16 17:26 ` Jan Blunck
2017-02-17 10:51 ` Olivier Matz
2017-02-17 12:49 ` Nélio Laranjeiro
2017-02-17 13:51 ` Jan Blunck
2017-02-18 5:48 ` Andrew Rybchenko
2017-02-17 13:38 ` Jan Blunck
2017-02-17 14:17 ` Olivier Matz
2017-02-17 18:42 ` Ananyev, Konstantin
2017-02-21 9:53 ` Olivier MATZ
2017-02-21 10:28 ` Ananyev, Konstantin
2017-02-20 9:27 ` Jan Blunck
2017-02-21 9:54 ` Olivier MATZ
2017-02-21 16:12 ` Jan Blunck
2017-02-21 16:38 ` Bruce Richardson
2017-02-21 17:04 ` Jan Blunck
2017-02-21 17:26 ` Ananyev, Konstantin
2017-02-21 19:17 ` Jan Blunck
2017-02-21 20:30 ` Ananyev, Konstantin
2017-02-21 21:51 ` Morten Brørup
2017-02-24 14:11 ` Olivier Matz
2017-02-24 14:00 ` Olivier Matz
2017-02-24 14:21 ` Bruce Richardson
2017-02-28 8:55 ` Jan Blunck
2017-02-28 9:05 ` Ananyev, Konstantin
2017-02-28 9:23 ` Olivier Matz
2017-02-28 9:33 ` Jan Blunck
2017-02-28 10:29 ` Ananyev, Konstantin
2017-02-28 10:50 ` Olivier Matz
2017-02-28 11:48 ` Ananyev, Konstantin
2017-02-28 12:28 ` Olivier Matz
2017-02-28 22:53 ` Ananyev, Konstantin
2017-03-02 16:46 ` Olivier Matz
2017-03-08 11:11 ` Ananyev, Konstantin
2017-03-20 9:00 ` Olivier Matz
2017-03-22 17:42 ` Ananyev, Konstantin
2017-03-24 8:35 ` Jerin Jacob
2017-03-24 13:35 ` Olivier Matz
2017-02-28 9:25 ` Jan Blunck
2017-02-19 23:45 ` Ananyev, Konstantin
2017-02-21 9:22 ` Morten Brørup
2017-02-21 9:54 ` Olivier MATZ
2017-03-08 9:41 ` [dpdk-dev] [PATCH 0/9] " Olivier Matz
2017-03-08 9:41 ` [dpdk-dev] [PATCH 1/9] mbuf: make segment prefree function public Olivier Matz
2017-03-08 9:41 ` [dpdk-dev] [PATCH 2/9] mbuf: make raw free " Olivier Matz
2017-03-08 9:41 ` [dpdk-dev] [PATCH 3/9] mbuf: set mbuf fields while in pool Olivier Matz
2017-03-31 11:21 ` Bruce Richardson
2017-03-31 11:51 ` Ananyev, Konstantin
2017-03-08 9:41 ` [dpdk-dev] [PATCH 4/9] drivers/net: don't touch mbuf next or nb segs on Rx Olivier Matz
2017-03-08 9:41 ` [dpdk-dev] [PATCH 5/9] mbuf: make rearm data address naturally aligned Olivier Matz
2017-03-08 9:41 ` [dpdk-dev] [PATCH 6/9] mbuf: use 2 bytes for port and nb segments Olivier Matz
2017-03-08 9:41 ` [dpdk-dev] [PATCH 7/9] mbuf: move sequence number in second cache line Olivier Matz
2017-03-08 9:42 ` [dpdk-dev] [PATCH 8/9] mbuf: add a timestamp field Olivier Matz
2017-04-04 10:29 ` [dpdk-dev] [PATCH 0/2] reduce writes to mbuf in ixgbe vRX Konstantin Ananyev
2017-04-07 15:13 ` Ferruh Yigit
2017-04-07 15:44 ` Ferruh Yigit
2017-04-09 22:56 ` Ananyev, Konstantin
2017-04-04 10:29 ` [dpdk-dev] [PATCH 1/2] net/ixgbe: eliminate mbuf write on rearm Konstantin Ananyev
2017-04-10 15:59 ` [dpdk-dev] [PATCH v2 0/2] reduce writes to mbuf in ixgbe vRX Konstantin Ananyev
2017-04-10 16:17 ` Ferruh Yigit
2017-04-10 15:59 ` [dpdk-dev] [PATCH v2 1/2] net/ixgbe: eliminate mbuf write on rearm Konstantin Ananyev
2017-04-10 15:59 ` [dpdk-dev] [PATCH v2 2/2] net/ixgbe: remove option to disable offload flags Konstantin Ananyev
2017-04-04 10:29 ` [dpdk-dev] [PATCH " Konstantin Ananyev
2017-03-08 9:42 ` [dpdk-dev] [PATCH 9/9] mbuf: reorder VLAN tci and buffer len fields Olivier Matz
2017-03-29 15:56 ` [dpdk-dev] [PATCH 0/9] mbuf: structure reorganization Olivier Matz
2017-03-29 16:03 ` Morten Brørup
2017-03-29 20:09 ` Bruce Richardson
2017-03-30 9:31 ` Bruce Richardson
2017-03-30 12:02 ` Olivier Matz
2017-03-30 12:23 ` Bruce Richardson
2017-03-30 16:45 ` Ananyev, Konstantin
2017-03-30 16:47 ` Ananyev, Konstantin
2017-03-30 18:06 ` Ananyev, Konstantin
2017-03-31 8:41 ` Olivier Matz
2017-03-31 9:58 ` Ananyev, Konstantin
2017-03-31 1:00 ` Ananyev, Konstantin
2017-03-31 7:21 ` Morten Brørup
2017-03-31 8:26 ` Olivier Matz
2017-03-31 8:41 ` Bruce Richardson
2017-03-31 8:59 ` Olivier Matz
2017-03-31 9:18 ` Ananyev, Konstantin
2017-03-31 9:36 ` Olivier Matz
2017-04-03 16:15 ` Thomas Monjalon
2017-04-04 7:58 ` Olivier MATZ
2017-04-04 8:53 ` Bruce Richardson
2017-03-31 9:23 ` Bruce Richardson
2017-03-31 11:18 ` Nélio Laranjeiro
2017-03-30 14:54 ` Andrew Rybchenko
2017-03-30 15:12 ` Jerin Jacob
2017-04-04 16:27 ` [dpdk-dev] [PATCH v2 0/8] " Olivier Matz
2017-04-04 16:28 ` [dpdk-dev] [PATCH v2 1/8] mbuf: make segment prefree function public Olivier Matz
2017-04-04 16:28 ` [dpdk-dev] [PATCH v2 2/8] mbuf: make raw free " Olivier Matz
2017-04-04 16:28 ` [dpdk-dev] [PATCH v2 3/8] mbuf: set mbuf fields while in pool Olivier Matz
2017-04-04 16:28 ` [dpdk-dev] [PATCH v2 4/8] drivers/net: don't touch mbuf next or nb segs on Rx Olivier Matz
2017-04-04 16:28 ` [dpdk-dev] [PATCH v2 5/8] mbuf: make rearm data address naturally aligned Olivier Matz
2017-04-04 16:28 ` [dpdk-dev] [PATCH v2 6/8] mbuf: use 2 bytes for port and nb segments Olivier Matz
2017-04-06 5:45 ` Yuanhan Liu
2017-04-18 13:03 ` Olivier MATZ
2017-07-04 7:54 ` Wang, Zhihong
2017-07-10 8:00 ` Olivier Matz
2017-07-10 8:15 ` Morten Brørup
2017-07-11 13:25 ` Wiles, Keith
2017-07-11 13:30 ` Morten Brørup
2017-07-11 15:05 ` Thomas Monjalon
2017-07-11 15:23 ` [dpdk-dev] [PATCH v2 6/8] mbuf: use 2 bytes for port and nbsegments Morten Brørup
2017-07-11 16:48 ` Wiles, Keith
2017-07-12 7:25 ` Morten Brørup
2017-07-12 9:02 ` Yang, Zhiyong
2017-07-12 9:50 ` Morten Brørup [this message]
2017-07-12 15:35 ` [dpdk-dev] [PATCH v2 6/8] mbuf: use 2 bytes for port andnbsegments Stephen Hemminger
2017-07-12 15:57 ` Morten Brørup
2017-07-12 16:23 ` Thomas Monjalon
2017-07-12 18:20 ` Wiles, Keith
2017-07-21 15:03 ` Bruce Richardson
2017-07-12 15:34 ` [dpdk-dev] [PATCH v2 6/8] mbuf: use 2 bytes for port and nbsegments Wiles, Keith
2017-07-11 13:34 ` [dpdk-dev] [PATCH v2 6/8] mbuf: use 2 bytes for port and nb segments Wiles, Keith
2017-07-11 13:46 ` Olivier MATZ
2017-04-04 16:28 ` [dpdk-dev] [PATCH v2 7/8] mbuf: move sequence number in second cache line Olivier Matz
2017-04-04 16:28 ` [dpdk-dev] [PATCH v2 8/8] mbuf: add a timestamp field Olivier Matz
2017-04-05 9:37 ` [dpdk-dev] [PATCH v2 0/8] mbuf: structure reorganization Thomas Monjalon
2017-04-05 9:46 ` Olivier MATZ
2017-04-05 9:48 ` Richardson, Bruce
2017-04-05 12:06 ` Ferruh Yigit
2017-04-14 13:10 ` Ferruh Yigit
2017-04-18 13:04 ` Olivier MATZ
2017-04-19 9:39 ` Thomas Monjalon
2017-04-19 12:28 ` Olivier MATZ
2017-04-19 12:56 ` Thomas Monjalon
2017-04-19 13:03 ` Ferruh Yigit
2017-04-19 13:12 ` Thomas Monjalon
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