On 04-Oct-18 12:43 PM, Alejandro Lucero wrote:
On Wed, Oct 3, 2018 at 1:50 PM Burakov, Anatoly <anatoly.bura...@intel.com <mailto:anatoly.bura...@intel.com>> wrote:On 31-Aug-18 1:50 PM, Alejandro Lucero wrote: > Linux kernel uses a really high address as starting address for > serving mmaps calls. If there exist addressing limitations and > IOVA mode is VA, this starting address is likely too high for > those devices. However, it is possible to use a lower address in > the process virtual address space as with 64 bits there is a lot > of available space. > > This patch adds an address hint as starting address for 64 bits > systems. > > Signed-off-by: Alejandro Lucero <alejandro.luc...@netronome.com <mailto:alejandro.luc...@netronome.com>> > --- <snip> > > mapped_addr = mmap(requested_addr, (size_t)map_sz, PROT_READ, > mmap_flags, -1, 0); > + > if (mapped_addr == MAP_FAILED && allow_shrink) Unintended whitespace change? Yes. I'll fix it. > *size -= page_sz; > - } while (allow_shrink && mapped_addr == MAP_FAILED && *size > 0); > + > + if (mapped_addr != MAP_FAILED && addr_is_hint && > + mapped_addr != requested_addr) { > + /* hint was not used. Try with another offset */ > + munmap(mapped_addr, map_sz); > + mapped_addr = MAP_FAILED; > + next_baseaddr = RTE_PTR_ADD(next_baseaddr, 0x100000000); Why not increment by page size? Sure, it could take some more time to allocate, but will result in less wasted memory.I though the same or even using smaller increments than hugepage size. Increment the address in such amount does not mean we are wasting memory but just leaving space if some mmap fails. I think it is better to leave as much as space as possible just in case the data allocated in the conflicted area would need to grow in the future.
Not sure i follow. Could you give an example of a scenario where leaving huge chunks of memory free would be preferable to just adding page size and starting from page-size-aligned address next time we allocate?
-- Thanks,Anatoly
-- Thanks, Anatoly
