[port 0] RX HW timestamp: 0x00001208f2a8d6c7, TCP timestamp: 0x669efc3b6a269469
(tsval: 1721695291, tsecr: 1780913257) (not LROed)
[port 0] RX HW timestamp: 0x669efc3b6a26946a, TCP timestamp: 0x669efc3b6a26946a
(tsval: 1721695291, tsecr: 1780913258) (LROed)
[port 0] RX HW timestamp: 0x669efc3b6a26946a, TCP timestamp: 0x669efc3b6a26946a
(tsval: 1721695291, tsecr: 1780913258) (LROed)
[port 0] RX HW timestamp: 0x669efc3b6a26946a, TCP timestamp: 0x669efc3b6a26946a
(tsval: 1721695291, tsecr: 1780913258) (LROed)
[port 0] RX HW timestamp: 0x00001208f2b05907, TCP timestamp: 0x669efc3b6a26946a
(tsval: 1721695291, tsecr: 1780913258) (not LROed)
[port 0] RX HW timestamp: 0x669efc3c6a26946a, TCP timestamp: 0x669efc3c6a26946a
(tsval: 1721695292, tsecr: 1780913258) (LROed)
[port 0] RX HW timestamp: 0x669efc3c6a26946a, TCP timestamp: 0x669efc3c6a26946a
(tsval: 1721695292, tsecr: 1780913258) (LROed)
[port 0] RX HW timestamp: 0x669efc3c6a26946a, TCP timestamp: 0x669efc3c6a26946a
(tsval: 1721695292, tsecr: 1780913258) (LROed)
[port 0] RX HW timestamp: 0x00001208f2b8f191, TCP timestamp: 0x669efc3c6a26946a
(tsval: 1721695292, tsecr: 1780913258) (not LROed)
[port 0] RX HW timestamp: 0x669efc3c6a26946b, TCP timestamp: 0x669efc3c6a26946b
(tsval: 1721695292, tsecr: 1780913259) (LROed)
[port 0] RX HW timestamp: 0x669efc3c6a26946b, TCP timestamp: 0x669efc3c6a26946b
(tsval: 1721695292, tsecr: 1780913259) (LROed)
[port 0] RX HW timestamp: 0x669efc3c6a26946b, TCP timestamp: 0x669efc3c6a26946b
(tsval: 1721695292, tsecr: 1780913259) (LROed)
[port 0] RX HW timestamp: 0x00001208f2c0689b, TCP timestamp: 0x669efc3c6a26946b
(tsval: 1721695292, tsecr: 1780913259) (not LROed)
[port 0] RX HW timestamp: 0x669efc3d6a26946b, TCP timestamp: 0x669efc3d6a26946b
(tsval: 1721695293, tsecr: 1780913259) (LROed)
[port 0] RX HW timestamp: 0x669efc3d6a26946b, TCP timestamp: 0x669efc3d6a26946b
(tsval: 1721695293, tsecr: 1780913259) (LROed)
[port 0] RX HW timestamp: 0x669efc3d6a26946b, TCP timestamp: 0x669efc3d6a26946b
(tsval: 1721695293, tsecr: 1780913259) (LROed)
[port 0] RX HW timestamp: 0x00001208f2c83627, TCP timestamp: 0x669efc3d6a26946b
(tsval: 1721695293, tsecr: 1780913259) (not LROed)
[port 0] RX HW timestamp: 0x669efc3d6a26946c, TCP timestamp: 0x669efc3d6a26946c
(tsval: 1721695293, tsecr: 1780913260) (LROed)
[port 0] RX HW timestamp: 0x669efc3d6a26946c, TCP timestamp: 0x669efc3d6a26946c
(tsval: 1721695293, tsecr: 1780913260) (LROed)
[port 0] RX HW timestamp: 0x669efc3d6a26946c, TCP timestamp: 0x669efc3d6a26946c
(tsval: 1721695293, tsecr: 1780913260) (LROed)
[port 0] RX HW timestamp: 0x00001208f2cfa33b, TCP timestamp: 0x669efc3d6a26946c
(tsval: 1721695293, tsecr: 1780913260) (not LROed)
[port 0] RX HW timestamp: 0x669efc3e6a26946c, TCP timestamp: 0x669efc3e6a26946c
(tsval: 1721695294, tsecr: 1780913260) (LROed)
[port 0] RX HW timestamp: 0x669efc3e6a26946c, TCP timestamp: 0x669efc3e6a26946c
(tsval: 1721695294, tsecr: 1780913260) (LROed)
[port 0] RX HW timestamp: 0x669efc3e6a26946c, TCP timestamp: 0x669efc3e6a26946c
(tsval: 1721695294, tsecr: 1780913260) (LROed)
[port 0] RX HW timestamp: 0x00001208f2d8605d, TCP timestamp: 0x669efc3e6a26946c
(tsval: 1721695294, tsecr: 1780913260) (not LROed)
[port 0] RX HW timestamp: 0x669efc3e6a26946d, TCP timestamp: 0x669efc3e6a26946d
(tsval: 1721695294, tsecr: 1780913261) (LROed)
[port 0] RX HW timestamp: 0x669efc3e6a26946d, TCP timestamp: 0x669efc3e6a26946d
(tsval: 1721695294, tsecr: 1780913261) (LROed)
[port 0] RX HW timestamp: 0x669efc3e6a26946d, TCP timestamp: 0x669efc3e6a26946d
(tsval: 1721695294, tsecr: 1780913261) (LROed)
[port 0] RX HW timestamp: 0x00001208f2dfd977, TCP timestamp: 0x669efc3f6a26946d
(tsval: 1721695295, tsecr: 1780913261) (not LROed)
[port 0] RX HW timestamp: 0x669efc3f6a26946d, TCP timestamp: 0x669efc3f6a26946d
(tsval: 1721695295, tsecr: 1780913261) (LROed)
[port 0] RX HW timestamp: 0x669efc3f6a26946d, TCP timestamp: 0x669efc3f6a26946d
(tsval: 1721695295, tsecr: 1780913261) (LROed)
[port 0] RX HW timestamp: 0x669efc3f6a26946d, TCP timestamp: 0x669efc3f6a26946d
(tsval: 1721695295, tsecr: 1780913261) (LROed)
[port 0] RX HW timestamp: 0x00001208f2e78fab, TCP timestamp: 0x669efc3f6a26946d
(tsval: 1721695295, tsecr: 1780913261) (not LROed)
Sincerely,
Junghan Yoon
On Jul 24, 2025, 5:40 PM +0900, Ivan Malov <ivan.ma...@arknetworks.am>, wrote:
On Thu, 24 Jul 2025, Yoon Junghan wrote:
I found the key difference: when TCP timestamps (RFC 7323) are
enabled on the TCP sender, the RX HW timestamp of LROed packets on the DPDK PMD
on middlebox
machine becomes inconsistent
or invalid. Is there a known limitation or erratum in the mlx5
driver or CX7 firmware regarding this?
Very interesting observation. So did you have TCP timestamps enabled on
those
sender NICs that match the receiver NICs that would fail to do HW
timestamp
and did you have it disabled on links where HW timestamp was OK on
receiver?
But in the case of LRO on such NICs that have wrong HW timestamp, is the
TCP
timestamp option present in a LROed packet and does it have accurate
value?
Regarding erratum, - I have to confess I'm not an expert in this
particular
driver. May be they have some official documentation regarding this
somewhere.
Thank you.
Sincerely,
Junghan Yoon
On Jul 24, 2025, 12:26 AM +0900, Ivan Malov
<ivan.ma...@arknetworks.am>, wrote:
On Thu, 24 Jul 2025, Yoon Junghan wrote:
I'm not sure I did well. All interface show the same result.
current settings:
tx_type 0
rx_filter 0
But that should mean.. no timestamping?
1) May be also check 'sudo ethtool -T <ifname>'.
2) May be try to enable 'sudo hwstamp_ctl -i <ifname> -r 1'.
Thank you.
Sincerely,
Junghan Yoon
On 2025년 7월 23일 PM 11:19 +0900, Ivan Malov
<ivan.ma...@arknetworks.am>, wrote:
On Wed, 23 Jul 2025, Yoon Junghan wrote:
I isolated port 1 using -a option for EAL parameter and got the
similar result.
Note that port 1 becomes port 0 in this time.
[port 0] RX HW timestamp: 0x3eac4214bc574368 (LROed)
[port 0] RX HW timestamp: 0x3eac4214bc574368 (LROed)
[port 0] RX HW timestamp: 0x3eac4214bc574368 (LROed)
[port 0] RX HW timestamp: 0x3eac4214bc574368 (LROed)
[port 0] RX HW timestamp: 0x00042819272fad (not LROed)
[port 0] RX HW timestamp: 0x000428192e6e77 (not LROed)
[port 0] RX HW timestamp: 0x000428192e7f01 (not LROed)
[port 0] RX HW timestamp: 0x000428192e833d (not LROed)
FYI, I have 4 CX-7 on the same machine. (eth0 = port 0, ... eth3 =
port 3 in DPDK)
pci@0000:16:00.0 eth0 network MT2910 Family
[ConnectX-7]
pci@0000:40:00.0 eth1 network MT2910 Family
[ConnectX-7]
pci@0000:6a:00.0 eth2 network MT2910 Family
[ConnectX-7]
pci@0000:94:00.0 eth3 network MT2910 Family
[ConnectX-7]
Among them, only the first CX-7 shows consistent timestamp
regardless of LRO.
Does 'sudo hwstamp_ctl -i <ifname>' show consistent results across
all the NICs?
Thank you.
Sincerely,
Junghan Yoon
On 2025년 7월 23일 PM 10:28 +0900, Ivan Malov
<ivan.ma...@arknetworks.am>, wrote:
On Wed, 23 Jul 2025, Yoon Junghan wrote:
Thank you for quick response.
1) They are different NICs. Not in the same board. Separate
adapters in different PCIe slots.
2) My DPDK app uses 4 separate ports; port 0, port 1, port 2, and
port 3. They are all on different boards. Thus, they are running at the same
time.
Excellent. I apologise for one more dumb question, but does
isolating the very
specific NIC (so that DPDK does not grab the other ones) that is
known to give
strange timestamps, result in the same/unexpected behaviour? Just
to make sure.
Thank you.
Sincerely,
Junghan Yoon
On 2025년 7월 23일 PM 10:09 +0900, Ivan Malov
<ivan.ma...@arknetworks.am>, wrote:
Hello,
On Wed, 23 Jul 2025, Yoon Junghan wrote:
Hello,
As advised, I tested hardware timestamps with LRO enabled on our
ConnectX-7 NICs. However, the timestamps of LROed packets still show
inconsistent and abnormally
large
gaps from normal
packets.
Interestingly, I found this issue does not appear on all CX-7 NICs.
Even with identical DPDK code, firmware version (28.43.2566), and hardware
models from the
same
manufacturer, only
specific NICs exhibit this inconsistency.
I have confirmed that:
* All NICs use the same driver and firmware version.
* All NICs are of the same model (MCX75310AAS-NEA_Ax).
1) Do the two "NICs" ('port 0' and 'port 1' from below printout)
represent two
different ports/PFs of the same physical 'board'/'adapter card' in
fact?
2) If (1) is true, were the results obtained by running the
application on both
ports simultaneously (both managed by the DPDK at the same time)?
(just to clarify, -- I'm confused by the fact that the NIC driver
itself seems
to invoke 'rte_mbuf_dyn_rx_timestamp_register' for each new RxQ
rather than call
it once and then look-up and reuse the existing offsets for more
ports/queue ).
Thank you.
* The issue occurs only when LRO is enabled together with RX
hardware timestamping.
* Disabling LRO eliminates the issue.
I would appreciate any insight into how this behavior can occur on
only some ports despite same software and hardware setup.
Below is my code snippet.
```c
/*----------------------------------------------------------------------------*/
static inline int
is_timestamp_enabled(struct rte_mbuf *mbuf)
{
static uint64_t timestamp_rx_dynflag = 0;
int timestamp_rx_dynflag_offset;
if (!timestamp_rx_dynflag)
{
timestamp_rx_dynflag_offset =
rte_mbuf_dynflag_lookup(RTE_MBUF_DYNFLAG_RX_TIMESTAMP_NAME, NULL);
if (timestamp_rx_dynflag_offset < 0)
{
return 0;
}
timestamp_rx_dynflag =
RTE_BIT64(timestamp_rx_dynflag_offset);
}
return mbuf->ol_flags & timestamp_rx_dynflag;
}
/*----------------------------------------------------------------------------*/
static inline rte_mbuf_timestamp_t *
get_timestamp(struct rte_mbuf *mbuf)
{
static int timestamp_dynfield_offset = -1;
if (timestamp_dynfield_offset < 0)
{
timestamp_dynfield_offset =
rte_mbuf_dynfield_lookup(RTE_MBUF_DYNFIELD_TIMESTAMP_NAME, NULL);
if (timestamp_dynfield_offset < 0)
{
return 0;
}
}
return RTE_MBUF_DYNFIELD(mbuf,
timestamp_dynfield_offset,
rte_mbuf_timestamp_t *);
}
/*----------------------------------------------------------------------------*/
static inline rte_mbuf_timestamp_t *
get_rx_hw_timestamp(struct rte_mbuf *pkt)
{
if (!is_timestamp_enabled(pkt))
{
printf("rx_hw_timestamp not enabled in mbuf!\n");
return NULL;
}
return get_timestamp(pkt);
}
```
My DPDK application prints logs as below.
```c
/* parse HW timestamp */
rte_mbuf_timestamp_t *rx_timestamp = get_rx_hw_timestamp(pkt);
printf("[port %d] RX HW timestamp: %#016lx %s\n",
pctx->port_id,
*rx_timestamp,
pkt->ol_flags & PKT_RX_LRO ? "(LROed)" : "(not LROed)");
```
Below are observations from two CX-7 ports under identical
conditions.
Normal NIC (port 0):
[port 0] RX HW timestamp: 0x00007dcd2d185b (LROed)
[port 0] RX HW timestamp: 0x00007dcd2d1911 (LROed)
[port 0] RX HW timestamp: 0x00007dcd2d19c9 (LROed)
[port 0] RX HW timestamp: 0x00007dcd2d37ca (LROed)
[port 0] RX HW timestamp: 0x00007dcd2d4cb3 (not LROed)
[port 0] RX HW timestamp: 0x00007dcd2d4cb3 (not LROed)
[port 0] RX HW timestamp: 0x00007dcd30e019 (not LROed)
[port 0] RX HW timestamp: 0x00007dcd3280bb (not LROed)
Erroneous NIC (port 1):
Below is erroneous NIC's timestamp.
[port 1] RX HW timestamp: 0x3e6eef91bc19f0fd (LROed)
[port 1] RX HW timestamp: 0x3e6eef91bc19f0fd (LROed)
[port 1] RX HW timestamp: 0x3e6eef91bc19f0fd (LROed)
[port 1] RX HW timestamp: 0x3e6eef91bc19f0fd (LROed)
[port 1] RX HW timestamp: 0x000080691b7557 (not LROed)
[port 1] RX HW timestamp: 0x000080691e2311 (not LROed)
[port 1] RX HW timestamp: 0x00008069357553 (not LROed)
[port 1] RX HW timestamp: 0x0000806936e8c1 (not LROed)
As shown above, non-LRO packets consistently have normal hardware
timestamps on both NICs. However, on port 1, all LROed packets return a fixed,
invalid timestamp
(0x3e6eef91bc19f0fd),
which is clearly inconsistent.
I have also confirmed that other dynfields (rather than dynfield[1]
and dynfield[2]) are unused.
Sincerely,
Junghan Yoon
On Jul 22, 2025, 5:31 PM +0900, Ivan Malov
<ivan.ma...@arknetworks.am>, wrote:
Hello,
On Tue, 22 Jul 2025, Yoon Junghan wrote:
Hello,
I'm currently using DPDK 20.11 with a ConnectX-7 NIC, and I'm
trying to retrieve RX hardware timestamps using
`rte_mbuf_dyn_rx_timestamp_register()`.
Does the application invoke 'rte_mbuf_dyn_rx_timestamp_register' on
its own? If
yes, consider to replace this with invocations of APIs [1] (with
field name [2])
and [3] (with flag name [4]). For an example, please refer to [5]
and [6].
This is because, as per [7], the driver in question might
'register' the field
and the flag on its own, in response to 'DEV_RX_OFFLOAD_TIMESTAMP'
request, so,
the user application should look up the field/flag, not 'register'
it afresh.
If this does not help, then consider to clarify whether the
timestamps are
accurate (and whether the flag is seen in the mbufs) when LRO is
not enabled.
[1]
https://doc.dpdk.org/api-20.11/rte__mbuf__dyn_8h.html#a6adf9b352a83e7d521fd6aa04e305b1c
[2]
https://doc.dpdk.org/api-20.11/rte__mbuf__dyn_8h.html#a5159b2d34fa801d171ed0ccce451121b
[3]
https://doc.dpdk.org/api-20.11/rte__mbuf__dyn_8h.html#a89d835027034f76a27eb2afe7987ae35
[4]
https://doc.dpdk.org/api-20.11/rte__mbuf__dyn_8h.html#a831d7066c7193788351797a65186848a
[5]
https://github.com/DPDK/dpdk/blob/d69724b1dcc69784bcef00b96597469b7f6e6207/app/test-pmd/util.c#L44
[6]
https://github.com/DPDK/dpdk/blob/d69724b1dcc69784bcef00b96597469b7f6e6207/app/test-pmd/util.c#L60
[7]
https://github.com/DPDK/dpdk/blob/d69724b1dcc69784bcef00b96597469b7f6e6207/drivers/net/mlx5/mlx5_rxq.c#L1743
Thank you.
When LRO is enabled, I notice that LROed mbufs seem to share
identical timestamp values, and the timestamps are unexpectedly large or
inconsistent. This raises
the question of whether
LRO is interfering with the correctness of the RX HW timestamps.
I’d appreciate any clarification on whether HW RX timestamping is
reliable when LRO is enabled on this platform, or if LRO should be just
disabled for accurate
per-packet timestamping.
Sincerely,
Junghan Yoon
