[dpdk-dev] eal: DPDK: 18.11.6 version rte_eal_init() function cleans the runtime directory in 5.4.35 kernel
Burakov, Anatoly
anatoly.burakov at intel.com
Thu Oct 15 20:01:09 CEST 2020
On 15-Oct-20 5:14 PM, Mohakud, Amiya Ranjan wrote:
> + Souvik
>
> *From:*Mohakud, Amiya Ranjan
> *Sent:* 15 October 2020 21:38
> *To:* Burakov, Anatoly <anatoly.burakov at intel.com>; dpdk-dev <dev at dpdk.org>
> *Subject:* RE: [dpdk-dev] eal: DPDK: 18.11.6 version rte_eal_init()
> function cleans the runtime directory in 5.4.35 kernel
>
> Hi Anatoly - Thanks for helping on this.
>
> I am not aware, where the primary process re-creates the files. Can you
> please point me to that? As per my code browsing and understanding, I
> can see, fbarray_memzone file gets created in
> rte_eal_memzone_init()->rte_fbarray_init() and it stays there till
> eal_clean_runtime_dir() gets called towards end of rte_eal_init(). This
> does not get deleted in 4.19 kernel, but in 5.4, it does.
>
> /I'm not sure i understand. Primary process is supposed to clear the
> files. It will then recreate them. Are you suggesting that it's clearing
> them *after* it has created them?/
>
> /
> /Going by my observation, the file highlighted below gets deleted by the
> time rte_eal_init() is over.
>
> srwxr-xr-x 1 root root 0 Oct 15 11:24 mp_socket
>
> -rw------- 1 root root 12432 Oct 15 11:24 hugepage_info
>
> -rw------- 1 root root 188416 Oct 15 11:24 fbarray_memzone
>
> -rw------- 1 root root 397312 Oct 15 11:24 fbarray_memseg-2048k-0-1
>
> -rw------- 1 root root 397312 Oct 15 11:24 fbarray_memseg-2048k-0-0
>
> -rw------- 1 root root 397312 Oct 15 11:24 fbarray_memseg-2048k-0-3
>
> -rw------- 1 root root 397312 Oct 15 11:24 fbarray_memseg-2048k-0-2
>
> -rw------- 1 root root 16529 Oct 15 11:24 config
>
> Please reach out to me for further clarification.
>
> Regards
>
> Amiya
Hi,
Sorry, yes, you're right (it's been a while since i looked at the code),
it removes unused stuff at the end of init. There's even a comment
explaining why that's done :D
It sounds like closing the file descriptor also drops the lock. This
locking business is a huge pain because we have to support old kernels
which don't have the only sane file locking implementation that Linux has.
While i wouldn't go as far as to say "this is a kernel regression" as
most likely it's me who's at fault here, but this definitely shouldn't
happen. Unfortunately, i won't be online for the next two weeks, but
i'll definitely look into this after i'm back, so thanks for your report.
--
Thanks,
Anatoly
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