On Mon, May 11, 2020 at 01:54:48PM +0000, liweihang wrote: > Hi All, > > I have two questions about masked atomic (Masked Compare and Swap & MFetchAdd): > > 1. The kernel now supports masked atomic, but the it does not support atomic > operation. Is the masked atomic valid in kernel currently? Yes, it is valid, but probably has a very little real value for the kernel ULPs. I see code in the RDS that uses atomics, but it says nothing to me, because upstream RDS and version in-real-use are completely different. > 2. In the userspace, ofed does not have the corresponding opcode for the masked > atomic (IB_WR_MASKED_ATOMIC_CMP_AND_SWP, IB_WR_MASKED_ATOMIC_FETCH_AND_ADD), > and ibv_send_wr also has no related data segment for it. How to support it in > userspace? ibv_send_wr is not extensible, so the real solution will need to extend ibv_wr_post() [1] with specific and new post builders. Thanks [1] https://github.com/linux-rdma/rdma-core/blob/master/libibverbs/man/ibv_wr_post.3.md > > Thanks > Weihang
