Re: [dpdk-users] DPDK and isolcpus

[Stephen Hemminger <stephen@networkplumber.org>]

On Fri, 26 Jul 2019 22:50:47 +0800
曾懷恩 <the@csie.io> wrote:

> Hi Filip,
> 
> Do you use Mellanox NIC?
> 
> In my experience, rte_lcore_count only counts those lcores that are not isolated when using mlx5 driver.
> 
> And Intel ixgbe counts lcores correctly even I use isolcpus flag
> 
> BR, 
> 
> Sent from my iPhone
> 
> > From: Filip Janiszewski <contact@filipjaniszewski.com>
> > To: "users@dpdk.org" <users@dpdk.org>
> > Subject: [dpdk-users] DPDK and isolcpus
> > Message-ID:
> >    <e98abf2a-b1cf-5fee-7929-778f70390d1d@filipjaniszewski.com>
> > Content-Type: text/plain; charset=iso-8859-15
> > 
> > Hi,
> > 
> > I've configured a bunch of my box cores with isolcpus and nohz_full in
> > the attempt to squeeze a little more performance out of them, but,
> > apparently I can't use those core in DPDK anymore as it seems that
> > rte_lcore_count reports only core which are not isolated, also I can't
> > launch any thread (rte_eal_remote_launch) on those cores.
> > 
> > In my understanding
> > (http://doc.dpdk.org/spp-18.02/setup/performance_opt.html) I should be
> > able to "Use the isolcpus Linux kernel parameter to isolate them from
> > Linux scheduler to reduce context switches. It prevents workloads of
> > other processes than DPDK running on reserved cores with isolcpus
> > parameter." but can't make it work.
> > 
> > Which is the correct way to bind DPDK threads to isolated cpus?
> > 
> > Thanks
> > 
> > -- 
> > BR, Filip
> > +48 666 369 823
> > 
> > 
> > End of users Digest, Vol 196, Issue 5
> > *************************************  

The default behavior of DPDK is to use all CPU's it finds.
To use isolated CPU's you need to pass the cpu's to use on the command line.

dpdk-XXX -l 4-7 ...