DPDK hugepages

[Cliff Burdick]

>
>
> On Thu, 25 May 2023 05:36:02 +0000
> "Lombardo, Ed" <Ed.Lombardo at netscout.com> wrote:
>
> > Hi,
> > I have two DPDK processes in our application, where one process
> allocates 1024 2MB hugepages and the second process allocates 8 1GB
> hugepages.
> > I am allocating hugepages in a script before the application starts.
> This is to satisfy different configuration settings and I don't want to
> write to grub when second DPDK process is enabled or disabled.
> >
> > Script that preconditions the hugepages:
> > Process 1:
> > mkdir /mnt/huge
> > mount -t hugetlbfs -o pagesize=2M nodev /mnt/huge
> > echo  1024  >
> /sys/devices/system/node/node0/hugepages/hugepages-2048kB/nr_hugepages
> >
> > Process 2:
> > mkdir /dev/hugepages-1024
> > mount -t hugetlbfs -o pagesize=1G none /dev/hugepages-1024
> > echo 8
> >/sys/devices/system/node/node0/hugepages/hugepages-1048576kB/nr_hugepages
> >
> >
> > Application -
> > Process 1 DPDK EAL arguments:
> > Const char *argv[] = { "app1", "-c", "7fc", "-n", "4", "--huge-dir",
> "/dev/hugepages-1024", "--proc-type", "secondary"};
> >
> > Process 2 DPDK EAL arguments:
> > const  char *dpdk_argv_2gb[6]  = {"app1 ", "-c0x2", "-n4" ,
> "--socket-mem=2048", "--huge-dir /mnt/huge", "--proc-type primary"};
> >
> > Questions:
> >
> >   1.  Does DPDK support two hugepage sizes (2MB and 1GB) sharing app1?
> This is a new scenario. I doubt it.
>
> It is possible to have two processes an a common hugepage pool.
>
>
> >   2.  Do I need to specify -proc-type for each Process shown above for
> argument to the rte_eal_init()?
> The problem is that DPDK uses a runtime directory to communicate.
>
> If you want two disjoint DPDK primary processes, you need to set the
> runtime directory.
>
> >   3.  I find the files in /dev/hugpages/rtemap_#s are not present once
> Process 2 hugepages-1G/nr_hugepages are set to 8, but when set value to 1
> the /dev/hugepages/rtemap_# files (1024) are present.  I can't see how to
> resolve this issue.  Any suggestions?
> >   4.  Do I need to set -socket-mem to the total memory of both
> Processes, or are they separately defined?  I have one NUMA node in this VM.
> >
> > Thanks,
> > Ed
>

To add to what Stephen said, to point to different directories for separate
processes use --file-prefix
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