Re: [dpdk-dev] Cannot mmap device resource in DPDK 1.7.0 multi-process/multi-thread

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

On Fri, Oct 24, 2014 at 01:21:08PM +0200, Mario Gianni wrote:
> Hi all, I have a problem since I updated to 1.7.0 version,
> I got a multi-process, multi-threaded application,
> In my application first I launch a master process, then I launch a secondary process with multiple threads in it
> Well, when the number of lcores reserved for the secondary process exceeds a certain number (eg. 4) i got an error in rte_eal_init() on the secondary process when it tries to map PCI memory:
>  
> EAL: pci_map_resource(): cannot mmap(12, 0x7ffff2e96000, 0x800000, 0x1000): Success (0x7ffff559b000)
> EAL: Cannot mmap device resource
> EAL: Error - exiting with code: 1
>     Cause: Requested device 0000:01:00.0 cannot be used
> 
> Can you help me?

This could be because the additional memory/stack space used by the pthreads 
for the cores in the secondary process is overlapping the space used in the 
primary process for hugepage or device memory. You could perhaps try adding 
a few cores to the primary process's coremask (and not using those cores) 
and see if it helps things. 
Alternatively there is a base-virtaddr parameter that can be passed to the 
primary process to try and adjust the starting address for it mapping 
memory. If you look at where it starts mapping memory right now, and then 
try hinting to it to maps the pages at a slightly higher or lower address 
and see if it helps.

/Bruce