From: "Ananyev, Konstantin" <konstantin.ananyev@intel.com>
To: Olivier Matz <olivier.matz@6wind.com>,
Jan Blunck <jblunck@infradead.org>
Cc: "dev@dpdk.org" <dev@dpdk.org>
Subject: Re: [dpdk-dev] [RFC 0/8] mbuf: structure reorganization
Date: Fri, 17 Feb 2017 18:42:01 +0000 [thread overview]
Message-ID: <2601191342CEEE43887BDE71AB9772583F118DD7@irsmsx105.ger.corp.intel.com> (raw)
In-Reply-To: <20170217151708.20bf4a49@platinum>
Hi guys,
> -----Original Message-----
> From: Olivier Matz [mailto:olivier.matz@6wind.com]
> Sent: Friday, February 17, 2017 2:17 PM
> To: Jan Blunck <jblunck@infradead.org>
> Cc: Ananyev, Konstantin <konstantin.ananyev@intel.com>; dev@dpdk.org
> Subject: Re: [dpdk-dev] [RFC 0/8] mbuf: structure reorganization
>
> Hi Jan,
>
> On Fri, 17 Feb 2017 14:38:32 +0100, Jan Blunck <jblunck@infradead.org>
> wrote:
> > On Fri, Feb 17, 2017 at 11:51 AM, Olivier Matz
> > <olivier.matz@6wind.com> wrote:
> > > Hi Jan,
> > >
> > > On Thu, 16 Feb 2017 18:26:39 +0100, Jan Blunck
> > > <jblunck@infradead.org> wrote:
> > >> On Thu, Feb 16, 2017 at 2:48 PM, Olivier Matz
> > >> <olivier.matz@6wind.com> wrote:
> > >> > On Mon, 6 Feb 2017 18:41:27 +0000, "Ananyev, Konstantin"
> > >> > <konstantin.ananyev@intel.com> wrote:
> > >> >> >
> > >> >> > The main changes are:
> > >> >> > - reorder structure to increase vector performance on some
> > >> >> > non-ia platforms.
> > >> >> > - add a 64bits timestamp field in the 1st cache line
> > >> >>
> > >> >> Wonder why it deserves to be in first cache line?
> > >> >> How it differs from seqn below (pure SW stuff right now).
> > >> >
> > >> > In case the timestamp is set from a NIC value, it is set in the
> > >> > Rx path. So that's why I think it deserve to be located in the
> > >> > 1st cache line.
> > >> >
> > >> > As you said, the seqn is a pure sw stuff right: it is set in a
> > >> > lib, not in a PMD rx path.
> > >> >
> > >>
> > >> If we talk about setting the timestamp value in the RX path this
> > >> implicitly means software timestamps. Hardware timestamping usually
> > >> works by letting the hardware inject sync events for coarse time
> > >> tracking and additionally injecting fine granular per-packet ticks
> > >> at a specific offset in the packet. Out of performance reasons I
> > >> don't think it makes sense to extract this during the burst and
> > >> write it into the mbuf again.
> > >
> > > From what I've understand, at least it does not work like this for
> > > mellanox NICs: timestamp is a metadata attached to a rx packet. But
> > > maybe they (and other NIC vendors interrested in the feature) can
> > > confirm or not.
> > >
> >
> > Mellanox NICs use a 48bit cycle counter split into a high and low
> > part. To convert the cycle values into a timestamp you need to
> > initialize and maintainer a timecounter that shifts the cycle count
> > e.g. nanosecs. IIRC Mellanox doesn't generate explicit clock events
> > but the cycle counter is large enough so that the user can easily
> > maintain the timecounter by manually updating it.
> >
> > >>
> > >> The problem with timestamps is to get the abstraction right wrt the
> > >> correction factors and the size of the tick vs. the timestamp in
> > >> the events injected. From my perspective it would be better to
> > >> extract the handling of timestamp data into a library with PMD
> > >> specific implementation of the conversions. That way the
> > >> normalized timestamp values can get extracted if they are present.
> > >> The mbuf itself would only indicate the presence of timestamp
> > >> metadata in that case.
> > >
> > > I agree however that we need to properly define the meaning of this
> > > field. My idea is:
> > >
> > > - the timestamp is in nanosecond
> > > - the reference is always the same for a given path: if the
> > > timestamp is set in a PMD, all the packets for this PMD will have
> > > the same reference, but for 2 different PMDs (or a sw lib), the
> > > reference would not be the same.
> > >
> > > I think it's enough for many use cases.
> > > We can later add helpers to compare timestamps with different
> > > references.
> >
> > My point is that I still doubt that it belongs into the first
> > cacheline. It requires accessing other structures for converting into
> > nanoseconds anyway. Optimally I would like to see this happening on
> > access instead but if that isn't achievable at least in a second step.
>
> Sorry, I don't really get your point. My comprehension of the timestamp
> usage in a PMD is as following:
>
> rx_burst(struct rxq *rxq, ...)
> {
> unsigned long factor = rxq->timestamp_factor;
> unsigned port = rxq->port;
>
> for each hw_desc {
> m = rte_pktmbuf_alloc(rxq->pool);
> m->len = hw_desc->len;
> m->port = port;
> m->ol_flags =
> ...
> m->timestamp = hw_desc->timestamp * factor;
> }
> ...
> }
>
> In that case, I think it deserves to be in the 1st cache line.
So you are saying that:
- for some HW that DPDK supports (mlx?) timestamp information
Is available in HW RX descriptor
- and as soon timestamp field will be available in mbuf, you plan
to populate it using this HW RXD field.
Is that so?
Konstantin
next prev parent reply other threads:[~2017-02-17 18:42 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 [this message]
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 ` [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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