Re: [dpdk-dev] Question about DPDK hugepage fd change

[Iain Barker <iain.barker@oracle.com>]

Original Message from: Burakov, Anatoly [mailto:anatoly.burakov@intel.com] 

>I just realized that, unless you're using --legacy-mem switch, one other 
>way to alleviate the issue would be to use --single-file-segments 
>option. This will still store the fd's, however it will only do so per 
>memseg list, not per page. So, instead of 1000's of fd's with 2MB pages, 
>you'd end up with under 10. Hope this helps!

Hi Anatoly,

Thanks for the update and suggestion. We did try using --single-file-segments previously. Although it lowers the amount of fd's allocated for tracking the segments as you noted, there is still a problem.

It seems that a .lock file is created for each huge page, not for each segment. So with 2MB pages the glibc limit of 1024 fd's is still exhausted quickly if there is ~2GB of 2MB huge pages.

Edwin can provide more details from his testing. In our case much sooner, as we already use >500 fd's for the application, just 1GB of 2MB huge pages is enough to hit the fd limit due to the .lock files.

Thanks.