[dpdk-dev] FreeBSD 13 Memory / Contigmem Issues With Booting

[dpdk-dev] FreeBSD 13 Memory / Contigmem Issues With Booting

[Brandon Lo]

Hi everyone,

I have been trying to expand the UNH IOL unit testing coverage over to
FreeBSD 13.
Following this documentation:
https://doc.dpdk.org/guides/freebsd_gsg/build_dpdk.html#loading-the-dpdk-contigmem-module

I compiled the contigmem kernel module from the latest DPDK v21.05 and
set the variables in /boot/loader.conf.
This results in a kernel trap 12 on boot with a machine that has 4GB
of RAM available and 1 GB assigned for contigmem.

If I only set the loader.conf to load the contigmem kernel module
without setting any variables, then it boots fine.
However, using these default settings, DPDK unit tests (fast-suite)
fail in some of the test cases.

Is this a memory-related issue where the virtual machine does not have
enough memory allocated (if so, how much RAM is needed?),
or is it related to compatibility issues between the different FreeBSD versions?

Thanks,
Brandon

-- 
Brandon Lo

UNH InterOperability Laboratory

21 Madbury Rd, Suite 100, Durham, NH 03824

blo@iol.unh.edu

www.iol.unh.edu

Re: [dpdk-dev] FreeBSD 13 Memory / Contigmem Issues With Booting

[Bruce Richardson]

On Wed, Jun 16, 2021 at 04:24:05PM -0400, Brandon Lo wrote:
> Hi everyone,
> 
> I have been trying to expand the UNH IOL unit testing coverage over to
> FreeBSD 13.
> Following this documentation:
> https://doc.dpdk.org/guides/freebsd_gsg/build_dpdk.html#loading-the-dpdk-contigmem-module
> 
> I compiled the contigmem kernel module from the latest DPDK v21.05 and
> set the variables in /boot/loader.conf.
> This results in a kernel trap 12 on boot with a machine that has 4GB
> of RAM available and 1 GB assigned for contigmem.
> 
> If I only set the loader.conf to load the contigmem kernel module
> without setting any variables, then it boots fine.
> However, using these default settings, DPDK unit tests (fast-suite)
> fail in some of the test cases.
> 
> Is this a memory-related issue where the virtual machine does not have
> enough memory allocated (if so, how much RAM is needed?),
> or is it related to compatibility issues between the different FreeBSD versions?
>
Given that the defaults if you don't specify a loader.conf value is to use
is 512MB, I suspect that it is indeed the case, and that the kernel is
struggling to find a single block of 1GB for use.

In terms of how much memory is needed, I'm not sure, it may take a bit of
trial and error to determine. What tests are needing more than 512MB of
RAM? I would have thought that that should have been plenty for most cases.

Another option to try rather than allocating a single 1GB block is to
attempt to create e.g. 2x 512MB or 3x 256MB blocks and see if that works,
or helps with the unit tests.

Regards,
/Bruce