Re: [dpdk-dev] [PATCH v4 1/1] fbarray: get fbarrays from containerized secondary

[David Marchand <david.marchand@redhat.com>]

On Fri, Oct 25, 2019 at 9:55 PM Yasufumi Ogawa <yasufum.o@gmail.com> wrote:
> >>
> >> The title does not reflect the observed issue.
> I would like to consider to revise it.
>
> >> I understand that secondary processeses can't be started from a docker
> >> container.
> I've confirmed that secondary process can be started as a container app
> with SPP, and DPDK v18.08 and v19.08. SPP is a multi-process app
> supporting container usecases.
> http://git.dpdk.org/apps/spp/

Sorry, I don't understand.
Do you mean the secondary processes can be run from containers without
this patch?
Or once this patch is applied?


>
> >> The patch title should reflect this.
> >>
> >> On Wed, Jul 24, 2019 at 10:20 AM <yasufum.o@gmail.com> wrote:
> >>>
> >>> From: Yasufumi Ogawa <ogawa.yasufumi@lab.ntt.co.jp>
> >>>
> >>> In secondary_msl_create_walk(), it creates a file for fbarrays with its
> >>> PID for reserving unique name among secondary processes. However, it
> >>> does not work if secondary is run as app container because each of
> >>> containerized secondary has PID 1. To reserve unique name, use hostname
> >>> instead of PID because hostname is assigned as a short form of 64
> >>> digits full container ID in docker.
> >>>
> >>> Cc: stable@dpdk.org
> >>
> >> I don't think we want to backport this behavior change.
> This issue was included from DPDK v18.08, and some users of SPP are
> still using stable 18.11. So, I would appreciate if you agree to backport.

This can be discussed later.
Ok to keep stable in CC: then.


>
> >>
> >>>
> >>> Signed-off-by: Yasufumi Ogawa <ogawa.yasufumi@lab.ntt.co.jp>
> >>> ---
> >>>   lib/librte_eal/linux/eal/eal_memalloc.c | 28 +++++++++++++++++++++++--
> >>>   1 file changed, 26 insertions(+), 2 deletions(-)
> >>>
> >>> diff --git a/lib/librte_eal/linux/eal/eal_memalloc.c b/lib/librte_eal/linux/eal/eal_memalloc.c
> >>> index 1f6a7c18f..356b304a8 100644
> >>> --- a/lib/librte_eal/linux/eal/eal_memalloc.c
> >>> +++ b/lib/librte_eal/linux/eal/eal_memalloc.c
> >>> @@ -1366,6 +1366,7 @@ secondary_msl_create_walk(const struct rte_memseg_list *msl,
> >>>          struct rte_memseg_list *primary_msl, *local_msl;
> >>>          char name[PATH_MAX];
> >>>          int msl_idx, ret;
> >>> +       char proc_id[33] = { 0 };  /* 32bytes is enough if using hostname */
> >>
> >> This variable only makes sense in the if (getpid() == 1) branch,
> >> please move it there, and see below comment about using gethostname().
> Sure. It works correctly in secondary app container and I should replace it.

Great, can you send a new version of this patch?

>
> >>
> >>>
> >>>          if (msl->external)
> >>>                  return 0;
> >>> @@ -1375,8 +1376,31 @@ secondary_msl_create_walk(const struct rte_memseg_list *msl,
> >>>          local_msl = &local_memsegs[msl_idx];
> >>>
> >>>          /* create distinct fbarrays for each secondary */
> >>> -       snprintf(name, RTE_FBARRAY_NAME_LEN, "%s_%i",
> >>> -               primary_msl->memseg_arr.name, getpid());
> >>> +       /* If run secondary in a container, the name of fbarray file should
> >>> +        * not be decided with pid because getpid() always returns 1.
> >>> +        * In docker, hostname is assigned as a short form of full container
> >>> +        * ID. So use hostname as unique ID among containers instead.
> >>
> >> I understand this is how it works for docker.
> >> Is this the same in other container environments?
> Umm... I've tested on other than docker because I don't have test
> environment. I am not sure which of container runtimes should be
> supported actually. I think it is enough as the first step to fix this
> issue of docker. Moreover, the essential problem is that getpid()
> returns 1 in docker or not.
>
> I am also not sure which of environments other than docker should be
> supported if necessary. What do you think?

No problem if you don't know.



--
David Marchand