Re: [dpdk-dev] [PATCH] eal: create runtime dir even when shared data is not used

[Bruce Richardson <bruce.richardson@intel.com>]

On Thu, Jul 01, 2021 at 04:43:48PM +0200, Morten Brørup wrote:
> > From: dev [mailto:dev-bounces@dpdk.org] On Behalf Of Bruce Richardson
> > Sent: Thursday, 1 July 2021 11.35
> > 
> > When multi-process is not wanted and DPDK is run with the "no-shconf"
> > flag, the telemetry library still needs a runtime directory to place
> > the
> > unix socket for telemetry connections. Therefore, rather than not
> > creating the directory when this flag is set, we can change the code to
> > attempt the creation anyway, but not error out if it fails. If it
> > succeeds, then telemetry will be available, but if it fails, the rest
> > of
> > DPDK will run without telemetry. This ensures that the "in-memory" flag
> > will allow DPDK to run even if the whole filesystem is read-only, for
> > example.
> > 
> > Signed-off-by: Bruce Richardson <bruce.richardson@intel.com>
> > ---
> >  lib/eal/linux/eal.c | 5 ++---
> >  1 file changed, 2 insertions(+), 3 deletions(-)
> > 
> > diff --git a/lib/eal/linux/eal.c b/lib/eal/linux/eal.c
> > index ba19fc6347..1e05ba3847 100644
> > --- a/lib/eal/linux/eal.c
> > +++ b/lib/eal/linux/eal.c
> > @@ -838,9 +838,8 @@ eal_parse_args(int argc, char **argv)
> >  		}
> >  	}
> > 
> > -	/* create runtime data directory */
> > -	if (internal_conf->no_shconf == 0 &&
> > -			eal_create_runtime_dir() < 0) {
> > +	/* create runtime data directory. In no_shconf mode, skip any
> > errors */
> > +	if (eal_create_runtime_dir() < 0 && internal_conf->no_shconf ==
> > 0) {
> >  		RTE_LOG(ERR, EAL, "Cannot create runtime directory\n");
> >  		ret = -1;
> >  		goto out;
> 
> When internal_conf->no_shconf == 1 and eal_create_runtime_dir() fails, DPDK will run without telemetry. Shouldn't it then be logged that telemetry is unavailable (and why it is unavailable)?
> 
There will be an error printed from the telemetry library about the socket
creation failing. However, it probably could do with being improved. I'll see
about creating a separate patch for that, since EAL should not be required
to know about what other libs may need a runtime dir or not.

/Bruce