Hi Anatoly, On Sat, Mar 03, 2018 at 01:45:48PM +0000, Anatoly Burakov wrote: > This patchset introduces dynamic memory allocation for DPDK (aka memory > hotplug). Based upon RFC submitted in December [1]. > > Dependencies (to be applied in specified order): > - IPC bugfixes patchset [2] > - IPC improvements patchset [3] > - IPC asynchronous request API patch [4] > - Function to return number of sockets [5] > > Deprecation notices relevant to this patchset: > - General outline of memory hotplug changes [6] > - EAL NUMA node count changes [7] > > The vast majority of changes are in the EAL and malloc, the external API > disruption is minimal: a new set of API's are added for contiguous memory > allocation for rte_memzone, and a few API additions in rte_memory due to > switch to memseg_lists as opposed to memsegs. Every other API change is > internal to EAL, and all of the memory allocation/freeing is handled > through rte_malloc, with no externally visible API changes. > > Quick outline of all changes done as part of this patchset: > > * Malloc heap adjusted to handle holes in address space > * Single memseg list replaced by multiple memseg lists > * VA space for hugepages is preallocated in advance > * Added alloc/free for pages happening as needed on rte_malloc/rte_free > * Added contiguous memory allocation API's for rte_memzone > * Integrated Pawel Wodkowski's patch for registering/unregistering memory > with VFIO [8] > * Callbacks for registering memory allocations > * Multiprocess support done via DPDK IPC introduced in 18.02 > > The biggest difference is a "memseg" now represents a single page (as opposed > to > being a big contiguous block of pages). As a consequence, both memzones and > malloc elements are no longer guaranteed to be physically contiguous, unless > the user asks for it at reserve time. To preserve whatever functionality that > was dependent on previous behavior, a legacy memory option is also provided, > however it is expected (or perhaps vainly hoped) to be temporary solution. > > Why multiple memseg lists instead of one? Since memseg is a single page now, > the list of memsegs will get quite big, and we need to locate pages somehow > when we allocate and free them. We could of course just walk the list and > allocate one contiguous chunk of VA space for memsegs, but this > implementation uses separate lists instead in order to speed up many > operations with memseg lists. > > For v1, the following limitations are present: > - FreeBSD does not even compile, let alone run > - No 32-bit support > - There are some minor quality-of-life improvements planned that aren't > ready yet and will be part of v2 > - VFIO support is only smoke-tested (but is expected to work), VFIO support > with secondary processes is not tested; work is ongoing to validate VFIO > for all use cases > - Dynamic mapping/unmapping memory with VFIO is not supported in sPAPR > IOMMU mode - help from sPAPR maintainers requested > > Nevertheless, this patchset should be testable under 64-bit Linux, and > should work for all use cases bar those mentioned above. > > [1] http://dpdk.org/dev/patchwork/bundle/aburakov/Memory_RFC/ > [2] http://dpdk.org/dev/patchwork/bundle/aburakov/IPC_Fixes/ > [3] http://dpdk.org/dev/patchwork/bundle/aburakov/IPC_Improvements/ > [4] http://dpdk.org/dev/patchwork/bundle/aburakov/IPC_Async_Request/ > [5] http://dpdk.org/dev/patchwork/bundle/aburakov/Num_Sockets/ > [6] http://dpdk.org/dev/patchwork/patch/34002/ > [7] http://dpdk.org/dev/patchwork/patch/33853/ > [8] http://dpdk.org/dev/patchwork/patch/24484/
I did a quick pass on your patches (unfortunately, I don't have the time to really dive in it). I have few questions/comments: - This is really a big patchset. Thank you for working on this topic. I'll try to test our application with it as soon as possible. - I see from patch 17 that it is possible that rte_malloc() expands the heap by requesting more memory to the OS? Did I understand well? Today, a good property of rte_malloc() compared to malloc() is that it won't interrupt the process (the worst case is a spinlock). This is appreciable on a dataplane core. Will it change? - It's not a big issue, but I have the feeling that the "const" statement is often forgotten in the patchset. I think it is helpful for both optimization, documentation and to detect bugs that modifies/free something that should not. I'm sending some other dummy comments as replies to patches. Thanks, Olivier
