From: Jan Blunck <jblunck@infradead.org>
To: "Ananyev, Konstantin" <konstantin.ananyev@intel.com>
Cc: "Richardson, Bruce" <bruce.richardson@intel.com>,
Olivier MATZ <olivier.matz@6wind.com>,
"dev@dpdk.org" <dev@dpdk.org>
Subject: Re: [dpdk-dev] [RFC 0/8] mbuf: structure reorganization
Date: Tue, 21 Feb 2017 20:17:42 +0100 [thread overview]
Message-ID: <CALe+Z01ozmTdWwxcc7mG+NhSV16K4+-Pe5uDWASzBBs5oMyh1g@mail.gmail.com> (raw)
In-Reply-To: <2601191342CEEE43887BDE71AB9772583F11B4CC@irsmsx105.ger.corp.intel.com>
On Tue, Feb 21, 2017 at 6:26 PM, Ananyev, Konstantin
<konstantin.ananyev@intel.com> wrote:
> Hi Jan,
>
>> -----Original Message-----
>> From: jblunck@gmail.com [mailto:jblunck@gmail.com] On Behalf Of Jan Blunck
>> Sent: Tuesday, February 21, 2017 5:05 PM
>> To: Richardson, Bruce <bruce.richardson@intel.com>
>> Cc: Olivier MATZ <olivier.matz@6wind.com>; Ananyev, Konstantin <konstantin.ananyev@intel.com>; dev@dpdk.org
>> Subject: Re: [dpdk-dev] [RFC 0/8] mbuf: structure reorganization
>>
>> On Tue, Feb 21, 2017 at 5:38 PM, Bruce Richardson
>> <bruce.richardson@intel.com> wrote:
>> > On Tue, Feb 21, 2017 at 05:12:12PM +0100, Jan Blunck wrote:
>> >>
>> >> Access through PMD specific function pointers should be relatively
>> >> fast on access. Modern architecture optimize that use case well
>> >> enough.
>> >>
>> > The cost of doing a function call per packet to access data starts to
>> > add up very, very fast. For the app, once the data is written to the
>> > mbuf, it should be in the L1 cache, giving very fast access to it in a
>> > few cycles. However, if a function call has to be made in order to do
>> > the read, that makes the read of that field many times more expensive.
>> >
>>
>> Exactly. Right now the timestamp normalization is done before writing
>> to each mbuf. Timestamps are usually read at most once ... if at all.
>
> Well we don't know for sure right?
> Someone can argue that there are plenty of scenarios when
> other fields might also never be used/updated (rss, vlan, etc).
>
> So, are you suggesting to do normalization later?
> If so, then what would be the benefit (data still need to be in mbuf)?
Yes, postponing normalization prevents you from doing unnecessary work
upfront. AFAIK not all NICs store timestamp data OOB, e.g. in CQ.
>
>> If you look at the analysis use cases they are read to be written to
>> persistent storage.
>
> Probably, or some statistic calculations, I guess.
> Or might be someone would use it to reorder packets before sending
> them out based on the timestamp, or might be something else.
Those timestamps are generated at arrival in the hardware. So that
order would be relative to the point of reception and in case you want
to resync flows that doesn't help much.
For statistics calculation and the resync use case you also might want
the raw timestamp (not normalized to nsec) and offload the
normalization out of band to reduce overall latency.
> It really hard to predict what use cases would come up (at least for me).
>
Indeed. I also just have the limited view of what I used timestamps
for so far. Who knows what use cases other people come up with in the
future.
next prev parent reply other threads:[~2017-02-21 19:17 UTC|newest]
Thread overview: 155+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-01-24 15:19 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 [this message]
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 ` [dpdk-dev] [PATCH v2 6/8] mbuf: use 2 bytes for port andnbsegments Morten Brørup
2017-07-12 15:35 ` 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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