[dpdk-dev] [PATCH v4 1/1] fbarray: get fbarrays from containerized secondary
Yasufumi Ogawa
yasufum.o at gmail.com
Fri Oct 25 21:54:56 CEST 2019
Hi David,
Thank you for your comments.
On 2019/10/26 0:36, David Marchand wrote:
> 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 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/
>> 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.
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.
>>
>>>
>>> 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().
Sure. It works correctly in secondary app container and I should replace it.
>>
>>>
>>> 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?
>>
>>
>>> + */
>>> + 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.
Yes. I should use gethostname() and replace hardcoded size with
HOST_NAME_MAX.
Thanks,
Yasufumi
>>
>>> + 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,
>
>
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