[dpdk-dev] [PATCH v2 2/5] mem: use address hint for mapping hugepages
Burakov, Anatoly
anatoly.burakov at intel.com
Wed Oct 3 14:50:05 CEST 2018
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.lucero at 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?
> *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.
--
Thanks,
Anatoly
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