RE: mlx5: imissed / out_of_buffer counter always 0

["Daniel Östman" <daniel.ostman@ericsson.com>]

Hi Maxime,

Sorry for the late reply, I've been on vacation.
Please see my answer below.

/ Daniel

> -----Original Message-----
> From: Maxime Coquelin <maxime.coquelin@redhat.com>
> Sent: Thursday, 22 June 2023 17:48
> To: Daniel Östman <daniel.ostman@ericsson.com>; Erez Ferber
> <erezferber@gmail.com>; Slava Ovsiienko <viacheslavo@nvidia.com>
> Cc: users@dpdk.org; Matan Azrad <matan@nvidia.com>;
> david.marchand@redhat.com
> Subject: Re: mlx5: imissed / out_of_buffer counter always 0
> 
> Hi,
> 
> On 6/21/23 22:22, Maxime Coquelin wrote:
> > Hi Daniel, all,
> >
> > On 6/5/23 16:00, Daniel Östman wrote:
> >> Hi Slava and Erez and thanks for your answers,
> >>
> >> Regarding the firmware, I’ve also deployed in a different OpenShift
> >> cluster were I see the exact same issue but with a different Mellanox
> >> NIC:
> >>
> >> Mellanox Technologies MT2892 Family - ConnectX-6 DX 2-port 100GbE
> >> QSFP56 PCIe Adapter
> >>
> >> driver: mlx5_core
> >>
> >> version: 5.0-0
> >> firmware-version: 22.36.1010 (DEL0000000027)
> >>
> >>  From what I can see the firmware is relatively new on that one?
> >
> > With below configuration:
> > - ConnectX-6 Dx MT2892
> > - Kernel: 6.4.0-rc6
> > - FW version: 22.35.1012 (MT_0000000528)
> >
> > The out-of-buffer counter is fetched via
> > mlx5_devx_cmd_queue_counter_query():
> >
> > [pid  2942] ioctl(17, RDMA_VERBS_IOCTL, 0x7ffcb15bcd10) = 0 [pid
> > 2942] write(1, "\n  ######################## NIC "..., 80) = 80 [pid
> > 2942] write(1, "  RX-packets: 630997736  RX-miss"..., 70) = 70 [pid
> > 2942] write(1, "  RX-errors: 0\n", 15) = 15 [pid  2942] write(1, "
> > RX-nombuf:  0         \n", 25) = 25 [pid  2942] write(1, "
> > TX-packets: 0          TX-erro"..., 60) = 60 [pid  2942] write(1,
> > "\n", 1)           = 1 [pid  2942] write(1, "  Throughput (since last
> > show)\n", 31) = 31 [pid  2942] write(1, "  Rx-pps:            0
> > "..., 106) = 106 [pid  2942] write(1, "
> > ##############################"..., 79) = 79
> >
> > It looks like we may miss some mlx5 kernel patches so that we can use
> > mlx5_devx_cmd_queue_counter_query() with RHEL?
> >
> > Erez, Slava, any idea on the patches that could be missing?
> 
> Above test was on baremetal as root, I get the same "working" behaviour on
> RHEL as root.
> 
> We managed to reproduce Daniel's with running the same within a container,
> enabling debug logs we have this warning:
> 
> mlx5_common: DevX create q counter set failed errno=121 status=0x2
> syndrome=0x8975f1
> mlx5_net: Port 0 queue counter object cannot be created by DevX - fall-back
> to use the kernel driver global queue counter.
> 
> Running the container as privileged solves the issue, and so does when
> adding SYS_RAWIO capability to the container.
> 
> Erez, Slava, is that expected to require SYS_RAWIO just to get a stat counter?
> 
> Daniel, could you try adding SYS_RAWIO to your pod to confirm you face the
> same issue?

Yes I can confirm what you are seeing when running in a cluster with Openshift 4.12 (RHEL 8.6) and with SYS_RAWIO or running as privileged.
But with privileged container I also need to run with UID 0 for it to work, is that what you are doing as well?
In both these cases the counter can be successfully retrieved through the DevX interface.

However, when running in a cluster with Openshift 4.10 (RHEL 8.4) I can not get it to work with any of these two approaches.

> Thanks in advance,
> Maxime
> > Regards,
> > Maxime
> >
> >>
> >> I tried setting dv_flow_en=0 (and saw that it was propagated to
> >> config->dv_flow_en) but it didn’t seem to help.
> >>
> >> Erez, I’m not sure what you mean by shared or non-shared mode in this
> >> case, however it seems it could be related to the fact that the
> >> container is running in a separate network namespace. Because the
> >> hw_counter directory is available on the host (cluster node), but not
> >> in the pod container.
> >>
> >> Best regards,
> >>
> >> Daniel
> >>
> >> *From:*Erez Ferber <erezferber@gmail.com>
> >> *Sent:* Monday, 5 June 2023 12:29
> >> *To:* Slava Ovsiienko <viacheslavo@nvidia.com>
> >> *Cc:* Daniel Östman <daniel.ostman@ericsson.com>; users@dpdk.org;
> >> Matan Azrad <matan@nvidia.com>; maxime.coquelin@redhat.com;
> >> david.marchand@redhat.com
> >> *Subject:* Re: mlx5: imissed / out_of_buffer counter always 0
> >>
> >> Hi Daniel,
> >>
> >> is the container running in shared or non-shared mode ?
> >>
> >> For shared mode, I assume the kernel sysfs counters which DPDK relies
> >> on for imissed/out_of_buffer are not exposed.
> >>
> >> Best regards,
> >>
> >> Erez
> >>
> >> On Fri, 2 Jun 2023 at 18:07, Slava Ovsiienko <viacheslavo@nvidia.com
> >> <mailto:viacheslavo@nvidia.com>> wrote:
> >>
> >>     Hi, Daniel
> >>
> >>     I would recommend to take the following action:
> >>
> >>     - update the firmware, 16.33.xxxx looks to be outdated a little bit.
> >>     Please, try 16.35.1012 or later.
> >>        mlx5_glue->devx_obj_create might succeed with the newer FW.
> >>
> >>     - try to specify dv_flow_en=0 devarg, it forces mlx5 PMD to use
> >>     rdma_core library for queue management
> >>       and kernel driver will  be aware about Rx queues being created
> >> and
> >>     attach them to the kernel counter set
> >>
> >>     With best regards,
> >>     Slava
> >>
> >>     *From:*Daniel Östman <daniel.ostman@ericsson.com
> >>     <mailto:daniel.ostman@ericsson.com>>
> >>     *Sent:* Friday, June 2, 2023 3:59 PM
> >>     *To:* users@dpdk.org <mailto:users@dpdk.org>
> >>     *Cc:* Matan Azrad <matan@nvidia.com <mailto:matan@nvidia.com>>;
> >>     Slava Ovsiienko <viacheslavo@nvidia.com
> >>     <mailto:viacheslavo@nvidia.com>>; maxime.coquelin@redhat.com
> >>     <mailto:maxime.coquelin@redhat.com>; david.marchand@redhat.com
> >>     <mailto:david.marchand@redhat.com>
> >>     *Subject:* mlx5: imissed / out_of_buffer counter always 0
> >>
> >>     Hi,
> >>
> >>     I’m deploying a containerized DPDK application in an OpenShift
> >>     Kubernetes environment using DPDK 21.11.3.
> >>
> >>     The application uses a Mellanox ConnectX-5 100G NIC through VFs.
> >>
> >>     The problem I have is that the ETH stats counter imissed (which
> >>     seems to be mapped to “out_of_buffer” internally in mlx5 PMD
> >> driver)
> >>     is 0 when I don’t expect it to be, i.e. when the application
> >> doesn’t
> >>     read the packets fast enough.
> >>
> >>     Using GDB I can see that it tries to access the counter through
> >>     /sys/class/infiniband/mlx5_99/ports/1/hw_counters/out_of_buffer
> >> but
> >>     the hw_counters directory is missing so it will just return a
> >> zero
> >>     value. I don’t know why it is missing.
> >>
> >>     When looking at mlx5_os_read_dev_stat() I can see that there is
> >> an
> >>     alternative way of reading the counter, through
> >>     mlx5_devx_cmd_queue_counter_query() but under the condition that
> >>     priv->q_counters are set.
> >>
> >>     It doesn’t get set in my case because
> >> mlx5_glue->devx_obj_create()
> >>     fails (errno 22) in mlx5_devx_cmd_queue_counter_alloc().
> >>
> >>     Have I missed something?
> >>
> >>     NIC info:
> >>
> >>     Mellanox Technologies MT27800 Family [ConnectX-5] - 100Gb 2-port
> >>     QSFP28 MCX516A-CCHT
> >>     driver: mlx5_core
> >>     version: 5.0-0
> >>     firmware-version: 16.33.1048 (MT_0000000417)
> >>
> >>     Please let me know if I need to provide more information.
> >>
> >>     Best regards,
> >>
> >>     Daniel
> >>