Re: [PATCHv12 1/3] rdmacg: Added rdma cgroup controller

From: Matan Barak
Date: Wed Sep 14 2016 - 04:30:25 EST

On 14/09/2016 10:06, Parav Pandit wrote:
Hi Dennis,

Do you know how would HFI1 driver would work along with rdma cgroup?

Hi Matan, Leon, Jason,
Apart from HFI1, is there any other concern?

I just wonder how things like RSS will work. For example, a RSS QP doesn't really have a queue (if I recall, it's connected to work queues via an indirection table). So, when a user creates such a QP, do you want to account it as a regular QP?
How are work queues accounted?

Or Patch is good to go?

4.8 dates are close by (2 weeks) and there are two git trees involved
(that might cause merge error to Linus) so if there are no issues, I
would like to make request to Doug to consider it for 4.8 early on.


On Mon, Sep 12, 2016 at 10:37 AM, Leon Romanovsky <leon@xxxxxxxxxx> wrote:
On Sun, Sep 11, 2016 at 11:52:35AM -0600, Jason Gunthorpe wrote:
On Sun, Sep 11, 2016 at 07:24:45PM +0200, Christoph Hellwig wrote:
I've posted some initial work toward a) a while ago, and once we

Did it get merged? Do you have a pointer?

Right, I remember that. Certainly the right direction

However, everything under verbs is not straightforward. The files in
userspace are not copies...


struct ibv_query_device {
__u32 command;
__u16 in_words;
__u16 out_words;
__u64 response;
__u64 driver_data[0];


struct ib_uverbs_query_device {
__u64 response;
__u64 driver_data[0];

We'll obviously need different strutures for the libibvers API
and the kernel interface in this case, and we'll need to figure out
how to properly translate them. I think a cast, plus compile time
type checking ala BUILD_BUG_ON is the way to go.

I'm not sure I follow, which would I cast?

BUILD_BUG_ON(sizeof(ibv_query_device) == sizeof(ib_uverbs_cmd_hdr) +


I'm thinking the best way forward might be to use a script and
transform userspace into:

struct ibv_query_device {
struct ib_uverbs_cmd_hdr hdr;
struct ib_uverbs_query_device cmd;

That would break the users of the interface.

Sorry, I mean doing this inside rdma-plumbing. Since the change is ABI
identical the modified libibverbs would still be binary compatible
with all providers but not source compatible. Since all kernel
supported providers are in rdma-plumbing we can add the '.cmd.' at the
same time.

The kernel uapi header would stay the same.

However automatically generating the user ABI from the kernel one
might still be a good idea in the long run.

My preference would be to try and use the kernel headers directly.

I thought the same, especially after realizing that they are almost
copy/paste from the vendor *-abi.h files.