On 20-Dec-18 5:18 PM, Thomas Monjalon wrote:

20/12/2018 17:16, Stephen Hemminger:

quoted

On Thu, 20 Dec 2018 15:32:37 +0000
Anatoly Burakov [off-list ref] wrote:

quoted

Currently, the only way to use externally allocated memory
is through rte_malloc API's. While this is fine for a lot
of use cases, it may not be suitable for certain other use
cases like manual memory management, etc.

This patchset adds another API to register memory segments
with DPDK (so that API's like ``rte_mem_virt2memseg`` could
be relied on by PMD's and such), but not create a malloc
heap out of them.

Aside from the obvious (not adding memory to a heap), the
other major difference between this API and the
``rte_malloc_heap_*`` external memory functions is the fact
that no DMA mapping is performed automatically, as well as
no mem event callbacks are triggered.

This really draws a line in the sand, and there are now two
ways of doing things - do everything automatically (using
the ``rte_malloc_heap_*`` API's), or do everything manually
(``rte_extmem_*`` and future DMA mapping API [1] that would
replace ``rte_vfio_dma_map``). This way, the consistency of
API is kept, and flexibility is also allowed.

[1] https://mails.dpdk.org/archives/dev/2018-November/118175.html

Where are the examples for this? Give a sample application maybe.

Also there are no test cases.

It looks to be a big task, but yes, would be nice to have test
of external memory allocation in DPDK unit tests.

I imagine if i submitted patches for this, since it's test code, it can 
go into rc1? Or is that considered a "feature"?

I don't think it will be a lot of code, there are only 4 new API calls. 
Extending extmem autotest should do the trick. Adding a new testpmd mode 
is also possible but less trivial, and can be postponed to 19.05.

-- 
Thanks,
Anatoly