On 2021/6/4 3:12, Jason Gunthorpe wrote: > On Thu, Jun 03, 2021 at 03:37:14PM +0800, Weihang Li wrote: > >> + hr_qp->has_mmaped = true; >> + pfn = context->uar.dwqe_page + pgoff; >> + prot = pgprot_device(vma->vm_page_prot); > > Why doesn't this use pgprot_writecombine() ? Does the devce really need > nGnRE not GRE? > > Jason > We use ST4 instructions to write 64 Bytes at a time, these instructions can guarantee the integrity of the data with nGnRE prot on our device. And with this prot, we can make direct wqe achieve better performance than NC. Thanks Weihang
