Re: [dpdk-dev] [PATCH v5 1/1] fbarray: fix duplicated fbarray file in secondary

["Ananyev, Konstantin" <konstantin.ananyev@intel.com>]

> -----Original Message-----
> From: Yasufumi Ogawa <yasufum.o@gmail.com>
> Sent: Wednesday, October 30, 2019 1:42 PM
> To: Ananyev, Konstantin <konstantin.ananyev@intel.com>; Burakov, Anatoly <anatoly.burakov@intel.com>; david.marchand@redhat.com
> Cc: dev@dpdk.org; stable@dpdk.org; Yasufumi Ogawa <ogawa.yasufumi@lab.ntt.co.jp>
> Subject: Re: [dpdk-dev] [PATCH v5 1/1] fbarray: fix duplicated fbarray file in secondary
> 
> On 2019/10/29 21:03, Ananyev, Konstantin wrote:
> >
> >
> >> -----Original Message-----
> >> From: dev <dev-bounces@dpdk.org> On Behalf Of yasufum.o@gmail.com
> >> Sent: Monday, October 28, 2019 8:08 AM
> >> To: Burakov, Anatoly <anatoly.burakov@intel.com>; david.marchand@redhat.com
> >> Cc: dev@dpdk.org; stable@dpdk.org; yasufum.o@gmail.com; Yasufumi Ogawa <ogawa.yasufumi@lab.ntt.co.jp>
> >> Subject: [dpdk-dev] [PATCH v5 1/1] fbarray: fix duplicated fbarray file in secondary
> >>
> >> 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 several secondaries run as app containers because each
> >> of containerized secondary has PID 1, and failed to reserve unique name
> >> other than first one. To reserve unique name in each of containers, use
> >> hostname instead of PID only if PID is 1.
> >>
> >> Cc: stable@dpdk.org
> >>
> >> Signed-off-by: Yasufumi Ogawa <yasufum.o@gmail.com>
> >> ---
> >>   lib/librte_eal/linux/eal/eal_memalloc.c | 15 +++++++++++++--
> >>   1 file changed, 13 insertions(+), 2 deletions(-)
> >>
> >> diff --git a/lib/librte_eal/linux/eal/eal_memalloc.c b/lib/librte_eal/linux/eal/eal_memalloc.c
> >> index af6d0d023..699079791 100644
> >> --- a/lib/librte_eal/linux/eal/eal_memalloc.c
> >> +++ b/lib/librte_eal/linux/eal/eal_memalloc.c
> >> @@ -1365,6 +1365,7 @@ 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[HOST_NAME_MAX] = { 0 };
> >>
> >>   	if (msl->external)
> >>   		return 0;
> >> @@ -1374,8 +1375,18 @@ 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.
> >
> >
> > I wonder why is that?
> > What will prevent user to do something like:
> > docker run -it --cpuset-cpus=7-8 -v /local/kananye1:/local/kananye1 ubuntu-dpdk-local:latest /bin/bash
> > And then start dpdk app manually within the container?
> Hi Konstantin,
> 
> Thank you for your comment.
> 
> My concern is running secondary as app container. In current
> implementation, the name of fbarray file is decided by using PID and it
> must be overlapped with other process because assigning PID is started
> from 1 in each of app container. This patch is to fix the issue.
> 
> I think it is doable running app from bash for testing, but not
> acceptable for a realistic usecase in which user manages several app
> containers.

User can have a bash script to start inside container first, that
would do some preparation work (setup env variables, etc.)....
Or some different scenario when user needs/wants to
spawn several processes within container. 
Inside the lib you can't assume that your usage scenario is the
only possible one. 
I think solution needs to be generic enough to cover all such cases.
BTW, why we can't always use hostname in fbarray format?

> 
> Regards,
> Yasufumi
> 
> >
> >> +	 * In docker, hostname is assigned as a short form of full container
> >> +	 * ID. So use hostname as unique ID among containers instead.
> >> +	 */
> >> +	if (getpid() == 1)
> >> +		gethostname(proc_id, HOST_NAME_MAX);
> >> +	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,
> >> --
> >> 2.17.1
> >