Hi Richard,
May I have your comments?
Hi Rodney,
Please see my comments inline.
Thanks a lot.
Best regards,
Yangbo Lu
> -----Original Message-----
> From: Rodney Cummings <rodney.cummi...@ni.com>
> Sent: Tuesday, October 15, 2019 1:12 AM
> To: Y.b. Lu <yangbo...@nxp.com>; linuxptp-devel@lists.sourceforge.net;
> Richard Cochran <richardcoch...@gmail.com>; Erik Hons <erik.h...@ni.com>
> Subject: RE: [RFC V2] Add IEEE 802.1AS-2011 time-aware bridge support
>
> Thanks Yangbo,
>
> I'd like to interject some overall comments/questions before digging into
> comments on the code.
>
> In my opinion I prefer this v2 (BC) over the previous v1 (TC).
>
> To me, it isn't so much about the name. It is more about aligning the code
> with
> the 802.1AS-2011 requirements ("shall"s). My employer (National Instruments)
> has been shipping our own BC-based fork of Linuxptp for years now (e.g. uses
> bc_dispatch() and bc_event() as is). That code has passed UNH-IOL
> conformance for 802.1AS-2011, performed well in 802.1AS-2011 plugfests (i.e.
> ICC, Avnu, ISPCS), and interoperated in customer applications with many other
> 802.1AS-2011 end-stations and bridges. I realize all of that is anecdotal, in
> that
> a TC-based fork of Linuxptp might have performed well also. Nevertheless, I'm
> concerned that a fully TC-based implementation would move the code away
> from conformance with 802.1AS-2011, and interoperation would break as a
> result.
>
[Y.b. Lu] To me, I think BC is proper after you clarified that, although I
thought it's TC before.
> Assuming the group is okay with BC, there is probably one other major
> question to answer before we go much further:
> Are we okay implementing the 802.1AS-2011 BC specifics in clock.c,
> or do we prefer to move most of that to a different file (bridge.c,
> gptp_relay.c, or whatever)?
>
[Y.b. Lu] I'm ok with any method. We can have Richard's comment.
>From my patch, there were not too much changes to reuse BC.
> There's a short list of items that make 802.1AS-2011 BC different from
> 1588-2008 P2P Default BC:
>
> 1. Transfer Sync / FollowUp differences from Slave (receive) to Master
> (transmit) ports.
> 2. Support distinct sync intervals on Slave and Master ports (like a typical
> BC).
>
> The v2 patch covers item 1 and 2, which are the core differences.
> Nevertheless,
> it might be good to keep other differences in mind (i.e. future patches)
> before
> we decide the preceding question:
>
[Y.b. Lu] Yes. The patch had core changes, so that it could be reviewed to
decide which method is good to add it in linuxptp.
> 3. Transfer Pdelay differences from Slave to Master ports (cumulative rate
> ratio).
[Y.b. Lu] I have already done that in patch. But it's different with standard.
I'm very confused on this, and doubt the standard.
See below changes.
+ /* Update follow_up TLV */
+ gm_rr *= nrr;
+ fui->cumulativeScaledRateOffset = gm_rr * POW2_41 - POW2_41;
I can't understand why standard gets rateRatio with,
rateRatio += (neighborRateRatio - 1.0);
not,
rateRatio *= neighborRateRatio;
As I understand, the rateRatio got from neighbor should be freq_gm /
freq_neighbor.
The neighborRateRato should be freq_neighbor / freq_cureent.
So rateRatio for current device (freq_gm / freq_cureent) should be rateRatio *
neighborRateRato.
I will appreciate if you can help me to get it right.
> 4. BMCA: Skip over UNCALIBRATED and PRE_MASTER states.
> 5. BMCA: Remove foreign master qualification (i.e. change threshold from 2 to
> 1).
> 6. Check performance requirement in 802.1AS-2011 B.1.1 for neighbor rate
> ratio computation.
> 7. BMCA: FAULTY causes a State Decision Event. 802.1AS-2011's methodology
> for faults is to avoid waiting in that FAULTY state in hopes that management
> will notice. Instead, 802.1AS moves on to search for a valid non-faulty state
> (SDE). If supported, the fault is logged so that management can notice later,
> but that logging isn't a requirement.
[Y.b. Lu] Thanks. No problem for me to generate patches to support these.
I don't think these will introduce much changes either. I tend to not create
new files for TAB/PRI.
>
> There's one other item in the upcoming revision (presumably 802.1AS-2020)
> that is not explicitly stated in 802.1AS-2011:
>
> 8. If-and-only-if the sync interval is the same for a Slave and Master port
> pair,
> "this PTP Port, when operating as a Master port, shall transmit a Sync as soon
> as possible after the Slave port received a Sync (ignoring syncInterval)." To
> Richard's credit, this is TC-like behavior. In the code, it presumably
> represents a
> call to tc_fwd_sync() as was done in Yangbo's v1 patch. When we dig into the
> details, there might be some 802.1AS-specifics, so maybe it will warrant a new
> gptp_relay_fwd_sync() function.
>
> Since 802.1AS-2020 isn't published yet, I'd be perfectly happy ignoring item 8
> for now. We can always revisit the issue later on.
>
> In the upcoming revision of 1588, all of items 1-8 are supported as options
> that a PTP Profile (like 802.1AS) can list as required. For example, the 1588
> revision allows UNCALIBRATED and PRE_MASTER to be skipped (whereas
> 1588-2008 requires those states). Therefore, items 1-8 will be conformant
> 1588 behavior that any profile can use. I mention this because if we want to
> avoid "gptp" or "802.1AS" in the naming of items 1-8, that sounds fine,
> because they are not necessarily exclusive to 802.1AS in the future.
[Y.b. Lu] Thank you for sharing these information. That's much helpful :)
>
> Rodney
> > -----Original Message-----
> > From: Yangbo Lu <yangbo...@nxp.com>
> > Sent: Monday, October 14, 2019 5:27 AM
> > To: linuxptp-devel@lists.sourceforge.net; Rodney Cummings
> > <rodney.cummi...@ni.com>; Richard Cochran
> <richardcoch...@gmail.com>;
> > Erik Hons <erik.h...@ni.com>
> > Cc: Yangbo Lu <yangbo...@nxp.com>
> > Subject: [EXTERNAL] [RFC V2] Add IEEE 802.1AS-2011 time-aware bridge
> > support
> >
> > This patch is to add IEEE 802.1AS-2011 time-aware bridge support based
> > on current BC clock type. It implements only time information relay,
> > and BMCA was not touched. To run it, the profile gPTP.cfg could be
> > used with multiple interfaces specified using -i option.
> >
> > The main code changes are,
> > - Create syfu_relay_info structure for time information relay.
> > - Implement port_syfu_relay_info_insert() to update follow_up (with TLV)
> > message with time information for relay.
> >
> > Signed-off-by: Yangbo Lu <yangbo...@nxp.com>
> > ---
> > Changes for v2:
> > - Implemented based on BC instead of TC.
> > ---
> > clock.c | 43 ++++++++++++++++++++++++++++++++++++-
> > clock.h | 45 +++++++++++++++++++++++++++++++++++++++
> > port.c | 75
> > +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++----
> > 3 files changed, 158 insertions(+), 5 deletions(-)
> >
> > diff --git a/clock.c b/clock.c
> > index 146576a..1865ecb 100644
> > --- a/clock.c
> > +++ b/clock.c
> > @@ -45,7 +45,6 @@
> > #include "util.h"
> >
> > #define N_CLOCK_PFD (N_POLLFD + 1) /* one extra per port, for the
> > fault timer */ -#define POW2_41 ((double)(1ULL << 41))
> >
> > struct port {
> > LIST_ENTRY(port) list;
> > @@ -123,6 +122,7 @@ struct clock {
> > int stats_interval;
> > struct clockcheck *sanity_check;
> > struct interface uds_interface;
> > + struct syfu_relay_info syfu_relay;
> > LIST_HEAD(clock_subscribers_head, clock_subscriber) subscribers; };
> >
> > @@ -1117,6 +1117,8 @@ struct clock *clock_create(enum clock_type type,
> > struct config *config,
> > }
> > }
> >
> > + memset(&c->syfu_relay, 0, sizeof(struct syfu_relay_info));
> > +
> > /* Initialize the parentDS. */
> > clock_update_grandmaster(c);
> > c->dad.pds.parentStats = 0;
> > @@ -1208,6 +1210,15 @@ void clock_follow_up_info(struct clock *c,
> > struct follow_up_info_tlv *f)
> > sizeof(c->status.lastGmPhaseChange));
> > }
> >
> > +static void clock_get_follow_up_info(struct clock *c, struct
> > +follow_up_info_tlv *f) {
> > + f->cumulativeScaledRateOffset = c-
> > >status.cumulativeScaledRateOffset;
> > + f->scaledLastGmPhaseChange = c->status.scaledLastGmPhaseChange;
> > + f->gmTimeBaseIndicator = c->status.gmTimeBaseIndicator;
> > + memcpy(&f->lastGmPhaseChange, &c->status.lastGmPhaseChange,
> > + sizeof(f->lastGmPhaseChange)); }
> > +
> > int clock_free_running(struct clock *c) {
> > return c->free_running ? 1 : 0;
> > @@ -1583,6 +1594,16 @@ void clock_peer_delay(struct clock *c, tmv_t
> > ppd, tmv_t req, tmv_t rx,
> > stats_add_value(c->stats.delay, tmv_dbl(ppd)); }
> >
> > +tmv_t clock_get_path_delay(struct clock *c) {
> > + return c->path_delay;
> > +}
> > +
> > +double clock_get_nrr(struct clock *c) {
> > + return c->nrr;
> > +}
> > +
> > int clock_slave_only(struct clock *c) {
> > return c->dds.flags & DDS_SLAVE_ONLY; @@ -1776,6 +1797,7 @@ static
> > void handle_state_decision_event(struct clock
> > *c)
> > c->path_delay = c->initial_delay;
> > c->nrr = 1.0;
> > fresh_best = 1;
> > + clock_disable_syfu_relay(c);
> > }
> >
> > c->best = best;
> > @@ -1847,3 +1869,22 @@ enum servo_state clock_servo_state(struct clock
> > *c) {
> > return c->servo_state;
> > }
> > +
> > +void clock_prepare_syfu_relay(struct clock *c, struct ptp_message *sync,
> > + struct ptp_message *fup)
> > +{
> > + c->syfu_relay.precise_origin_ts = timestamp_to_tmv(fup->ts.pdu);
> > + c->syfu_relay.correction = fup->header.correction;
> > + clock_get_follow_up_info(c, &c->syfu_relay.fup_info_tlv);
> > + c->syfu_relay.avail = 1;
> > +}
> > +
> > +void clock_disable_syfu_relay(struct clock *c) {
> > + c->syfu_relay.avail = 0;
> > +}
> > +
> > +struct syfu_relay_info *clock_get_syfu_relay(struct clock *c) {
> > + return &c->syfu_relay;
> > +}
> > diff --git a/clock.h b/clock.h
> > index 9d3133a..8ff1181 100644
> > --- a/clock.h
> > +++ b/clock.h
> > @@ -29,8 +29,18 @@
> > #include "tmv.h"
> > #include "transport.h"
> >
> > +#define POW2_41 ((double)(1ULL << 41))
> > +
> > struct ptp_message; /*forward declaration*/
> >
> > +struct syfu_relay_info {
> > + tmv_t precise_origin_ts;
> > + Integer64 correction;
> > + struct follow_up_info_tlv fup_info_tlv;
> > + /* Auxiliary info */
> > + int avail;
> > +};
> > +
> > /** Opaque type. */
> > struct clock;
> >
> > @@ -240,6 +250,20 @@ void clock_peer_delay(struct clock *c, tmv_t ppd,
> > tmv_t req, tmv_t rx,
> > double nrr);
> >
> > /**
> > + * Get the path delay as measured on a slave port.
> > + * @param c The clock instance.
> > + * @return The path delay as measured on a slave port.
> > + */
> > +tmv_t clock_get_path_delay(struct clock *c);
> > +
> > +/**
> > + * Get the neighbor rate ratio as measured on a slave port.
> > + * @param c The clock instance.
> > + * @return The neighbor rate ratio as measured on a slave
> > port.
> > + */
> > +double clock_get_nrr(struct clock *c);
> > +
> > +/**
> > * Set clock sde
> > * @param c A pointer to a clock instance obtained with
> > clock_create().
> > * @param sde Pass one (1) if need a decision event and zero if not.
> > @@ -359,4 +383,25 @@ void clock_check_ts(struct clock *c, uint64_t ts);
> > */
> > double clock_rate_ratio(struct clock *c);
> >
> > +/**
> > + * Prepare sync/follow_up relay.
> > + * @param c The clock instance.
> > + * @param sync The sync message.
> > + * @param fup The follow_up message.
> > + */
> > +void clock_prepare_syfu_relay(struct clock *c, struct ptp_message *sync,
> > + struct ptp_message *fup);
> > +
> > +/**
> > + * Disable sync/follow_up relay.
> > + * @param c The clock instance.
> > + */
> > +void clock_disable_syfu_relay(struct clock *c);
> > +
> > +/**
> > + * Get sync/follow_up relay information.
> > + * @param c The clock instance.
> > + * @return The sync/follow_up relay information.
> > + */
> > +struct syfu_relay_info *clock_get_syfu_relay(struct clock *c);
> > #endif
> > diff --git a/port.c b/port.c
> > index 07ad3f0..073e71a 100644
> > --- a/port.c
> > +++ b/port.c
> > @@ -1241,6 +1241,10 @@ static void port_syfufsm(struct port *p, enum
> > syfu_event event,
> > break;
> > case FUP_MATCH:
> > syn = p->last_syncfup;
> > + if (p->follow_up_info)
> > + clock_prepare_syfu_relay(p->clock, syn, m);
> > + else
> > + clock_disable_syfu_relay(p->clock);
> > port_synchronize(p, syn->hwts.ts, m->ts.pdu,
> > syn->header.correction,
> > m->header.correction,
> > @@ -1261,6 +1265,10 @@ static void port_syfufsm(struct port *p, enum
> > syfu_event event,
> > break;
> > case SYNC_MATCH:
> > fup = p->last_syncfup;
> > + if (p->follow_up_info)
> > + clock_prepare_syfu_relay(p->clock, m, fup);
> > + else
> > + clock_disable_syfu_relay(p->clock);
> > port_synchronize(p, m->hwts.ts, fup->ts.pdu,
> > m->header.correction,
> > fup->header.correction,
> > @@ -1450,6 +1458,60 @@ int port_tx_announce(struct port *p, struct
> > address
> > *dst)
> > return err;
> > }
> >
> > +static void port_syfu_relay_info_insert(struct port *p,
> > + struct ptp_message *sync,
> > + struct ptp_message *fup)
> > +{
> > + struct syfu_relay_info *syfu_relay = clock_get_syfu_relay(p->clock);
> > + struct follow_up_info_tlv *fui_relay = &syfu_relay->fup_info_tlv;
> > + struct follow_up_info_tlv *fui = follow_up_info_extract(fup);
> > + tmv_t ingress, egress, residence, path_delay;
> > + double gm_rr, nrr, rr;
> > + struct timestamp ts;
> > +
> > + if (syfu_relay->avail == 0)
> > + return;
> > +
> > + fup->follow_up.preciseOriginTimestamp =
> > + tmv_to_Timestamp(syfu_relay->precise_origin_ts);
> > + fup->header.correction = syfu_relay->correction;
> > +
> > + /* Calculate residence time. */
> > + ingress = clock_ingress_time(p->clock);
> > + egress = sync->hwts.ts;
> > + residence = tmv_sub(egress, ingress);
> > + rr = clock_rate_ratio(p->clock);
> > + if (rr != 1.0) {
> > + residence = dbl_tmv(tmv_dbl(residence) * rr);
> > + }
> > +
> > + gm_rr = 1.0 + (fui_relay->cumulativeScaledRateOffset + 0.0) /
> > POW2_41;
> > + nrr = clock_get_nrr(p->clock);
> > +
> > + /* Add corrected residence time into correction. */
> > + fup->header.correction += tmv_to_TimeInterval(residence) * gm_rr *
> > +nrr;
> > +
> > + /* Add corrected path delay into correction. */
> > + path_delay = clock_get_path_delay(p->clock);
> > + fup->header.correction += tmv_to_TimeInterval(path_delay) * gm_rr;
> > +
> > + /* Update follow_up TLV */
> > + gm_rr *= nrr;
> > + fui->cumulativeScaledRateOffset = gm_rr * POW2_41 - POW2_41;
> > + fui->scaledLastGmPhaseChange = fui_relay->scaledLastGmPhaseChange;
> > + fui->gmTimeBaseIndicator = fui_relay->gmTimeBaseIndicator;
> > + memcpy(&fui->lastGmPhaseChange, &fui_relay->lastGmPhaseChange,
> > + sizeof(fui->lastGmPhaseChange));
> > +
> > + ts.sec = fup->follow_up.preciseOriginTimestamp.seconds_msb;
> > + ts.sec = ts.sec << 32 | fup-
> > >follow_up.preciseOriginTimestamp.seconds_lsb;
> > + ts.nsec = fup->follow_up.preciseOriginTimestamp.nanoseconds;
> > + pr_debug("port %hu: syfu_relay info:", portnum(p));
> > + pr_debug("port %hu: precise_origin_ts %" PRIu64 ".%u", portnum(p),
> > ts.sec, ts.nsec);
> > + pr_debug("port %hu: correction %" PRId64, portnum(p), fup-
> > >header.correction >> 16);
> > + pr_debug("port %hu: fup_info %.9f", portnum(p), gm_rr);
> > +}
> > +
> > int port_tx_sync(struct port *p, struct address *dst) {
> > struct ptp_message *msg, *fup;
> > @@ -1543,10 +1605,15 @@ int port_tx_sync(struct port *p, struct
> > address
> > *dst)
> > fup->address = *dst;
> > fup->header.flagField[0] |= UNICAST;
> > }
> > - if (p->follow_up_info && follow_up_info_append(fup)) {
> > - pr_err("port %hu: append fup info failed", portnum(p));
> > - err = -1;
> > - goto out;
> > +
> > + if (p->follow_up_info) {
> > + if (follow_up_info_append(fup)) {
> > + pr_err("port %hu: append fup info failed", portnum(p));
> > + err = -1;
> > + goto out;
> > + }
> > +
> > + port_syfu_relay_info_insert(p, msg, fup);
> > }
> >
> > err = port_prepare_and_send(p, fup, TRANS_GENERAL);
> > --
> > 2.7.4
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