Re: [dpdk-dev] [PATCH] librte_eal: add APIs to speedup virt2iova/phys

[Dmitry Kozlyuk <dmitry.kozliuk@gmail.com>]

> On 20-Apr-20 12:09 PM, Li Feng wrote:
> > Using pread to replace lseek + read.
> > And add new APIs to reduce open/close/lseek system call frequency when the
> > user needs to convert a large range of virtual address space.
> >      - rte_mem_virt2iova_with_fd
> >      - rte_mem_virt2phy_with_fd
> > 
> > Currently it will be used by spdk in spdk_mem_register.
> > 
> > Signed-off-by: Li Feng <fengli@smartx.com>
> > ---  
> 
> These API's are IMO already on the verge of what's acceptable because of 
> the differences between PA, DPDK IOVA and external memory IOVA. I'm not 
> sure building on top of them is a good idea. It's also quite platform 
> specific - rte_mem_virt2phy could potentially work with Windows (and in 
> fact there was an RFC for it), but would this API work with Windows, 
> given that Windows doesn't have fd's? Should we perhaps replace fd's 
> with an opaque structure pointer, so that each platform-specific 
> implementation could dereference it the way it needs to, without 
> exposing internal details of the platform?

These new APIs are, in fact, Linux-specific. Doubtfully will Windows ever
benefit from it even with fd abstracted, though I can't say for FreeBSD. Given
the linked suggestion to move rte_vfio_container_dma_map/unmap to some
include/linux header, maybe these APIs could land there too?

	http://mails.dpdk.org/archives/dev/2020-April/164404.html

-- 
Dmitry Kozlyuk