Re: [dpdk-dev] [PATCH v2 0/4] Clean up EAL runtime data paths

["Van Haaren, Harry" <harry.van.haaren@intel.com>]

> From: dev [mailto:dev-bounces@dpdk.org] On Behalf Of Anatoly Burakov
> Sent: Monday, April 30, 2018 1:09 PM
> To: dev@dpdk.org
> Cc: Richardson, Bruce <bruce.richardson@intel.com>; thomas@monjalon.net
> Subject: [dpdk-dev] [PATCH v2 0/4] Clean up EAL runtime data paths
> 
> As has been suggested [1], all DPDK runtime paths should be put
> into a single place. This patchset accomplishes exactly that.
> 
> If running as root, all files will be put under /var/run/dpdk/<prefix>,
> otherwise they will be put under $XDG_RUNTIME_PATH/dpdk/<prefix>, or, if
> that environment variable is not defined, all files will go under
> /tmp/dpdk/<prefix>.
> 
> [1] http://dpdk.org/dev/patchwork/patch/38688/
> 
> v2:
> - Rebase on rc1
> 
> Anatoly Burakov (4):
>   eal: remove unused define
>   eal: rename function returning hugepage data path
>   eal: add directory for DPDK runtime data
>   eal: move all runtime data into DPDK runtime dir

<snip>


No full code review, high level comments:

We have to be careful in changing /var/run/.rte_config, which has always been
the default DPDK primary application lockfile. This has been used to identify
if a primary DPDK application is alive (see rte_eal_primary_proc_alive()) and
possibly the write-lock on this file is checked by other tools/utilities directly
without any DPDK function call.

Changing the filepath just before a release isn't a good idea - we should treat
this as an ABI/API break, as the change will break functionality in other projects
such as CollectD[1], which (by default ;) rely on the defaults. There is a config
file for CollectD to manually override the location, but this will cause headaches
from a usability POV.

I'm not opposed to the change - particularly as I gather the new memory subsystem
causes a number of lockfiles to be created - but we must do our due diligence and
give other projects fair-warning that this change is coming.

As such, I recommend this patchset in its current form (particularly patches 2,3,4)
to be deferred past 18.05.


-Harry


[1] https://github.com/collectd/collectd/blob/master/src/utils_dpdk.c#L46