Re: [dpdk-dev] [PATCH] eal/linuxapp: Add parameter to specify master lcore id

[Thomas Monjalon <thomas.monjalon@6wind.com>]

2014-11-03 13:02, Aaron Campbell:
> Hi Simon,
> 
> Thanks for the patch, this will be useful for us.  I responded separately to your original post with one suggestion.
> 
> Our application currently assumes that DPDK will assign the first bit set in the coremask to the master lcore.  As far as I can tell, this is hard-coded as of 1.7.1.  But we would like the ability for our application to specify any bit from the coremask to serve as the master lcore.
> 
> I don’t see any compatibility issues with this.  Existing applications should behave as before.
> 
> Thomas, could this be accepted for the 1.8 release?  Or will that only happen if the BSD side can be patched as well?

No need for BSD side patch because option management is now common between
BSD and Linux. I'm going to send an updated version of this patch.

> > On Jul 23, 2014, at 9:10 AM, Simon Kuenzer <simon.kuenzer@neclab.eu> wrote:
> > 
> > Hi all,
> > 
> > the only issue I could imagine is that current DPDK applications are
> > utilizing the implicit assumption that the master lcore is always set to
> > the first available lcore. I would consider this as a "bug" in the
> > application because it sets up its worker threads not "properly".
> > 
> > However, as far I could check it, the DPDK framework seems to cope with
> > it correctly.
> > It would be nice if somebody else could confirm my statement.
> > 
> > Thanks,
> > 
> > Simon
> > 
> > On 23.07.2014 10:53, Hiroshi Shimamoto wrote:
> >> Hi,
> >> 
> >>> Subject: Re: [dpdk-dev] [PATCH] eal/linuxapp: Add parameter to specify master lcore id
> >>> 
> >>> Hi Hiroshi,
> >>> 
> >>> 2014-07-22 23:40, Hiroshi Shimamoto:
> >>>> does anyone have interest in this functionality?
> >>>> 
> >>>> I think this is important and useful.
> >>>> Since we should care about core assignment to get high performance
> >>>> and the master lcore thread is special in DPDK, we will want to
> >>>> assign the master to the target core.
> >>>> For example, with hyperthreading I'd like to make a pair of packet
> >>>> processing threads into one physical core and separate the master
> >>>> thread which does some management.
> >>> 
> >>> Thank you for showing your interest.
> >>> Does it mean you carefully reviewed this patch? In this case, I'd appreciate
> >>> a note "Reviewed-by:".
> >> 
> >> Not yet deeply, wait a bit, we're testing this patch in our application.
> >> Will report if it works fine.
> >> 
> >> By the way, we should add the same code into the BSD code, right?
> >> 
> >> thanks,
> >> Hiroshi