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

[David Marchand]

On Fri, Oct 11, 2019 at 11:36 AM David Marchand
<david.marchand at redhat.com> wrote:
>
> Some comments.

ping.


>
> The title does not reflect the observed issue.
> I understand that secondary processeses can't be started from a docker
> container.
> The patch title should reflect this.
>
> On Wed, Jul 24, 2019 at 10:20 AM <yasufum.o at gmail.com> wrote:
> >
> > From: Yasufumi Ogawa <ogawa.yasufumi at 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 at dpdk.org
>
> I don't think we want to backport this behavior change.
>
> >
> > Signed-off-by: Yasufumi Ogawa <ogawa.yasufumi at 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().
>
> >
> >         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?
>
>
> > +        */
> > +       if (getpid() == 1) {
> > +               FILE *hn_fp;
> > +               hn_fp = fopen("/etc/hostname", "r");
>
> Why not use gethostname() ?
> Plus, this api defines the maximum size of the hostname as HOST_NAME_MAX bytes.
>
> > +               if (hn_fp == NULL) {
> > +                       RTE_LOG(ERR, EAL,
> > +                               "Cannot open '/etc/hostname' for secondary\n");
> > +                       return -1;
> > +               }
> > +
> > +               /* with docker, /etc/hostname just has one entry of hostname */
> > +               if (fscanf(hn_fp, "%32s", proc_id) == EOF) {
> > +                       fclose(hn_fp);
> > +                       return -1;
> > +               }
> > +               fclose(hn_fp);
> > +       } else
> > +               sprintf(proc_id, "%d", (int)getpid());
> > +
> > +       snprintf(name, RTE_FBARRAY_NAME_LEN, "%s_%s",
> > +                       primary_msl->memseg_arr.name, proc_id);
> >
> >         ret = rte_fbarray_init(&local_msl->memseg_arr, name,
> >                 primary_msl->memseg_arr.len,


-- 
David Marchand