#include "memory.hpp"

#include "fs.hpp"

#include <sys/mman.h>

namespace ixy {

static uint32_t huge_pg_id;

auto memory_allocate_dma(size_t size, bool require_contiguous) -> dma_memory {

debug("allocating dma memory via huge page");

// round up to multiples of 2 MB if necessary, this is the wasteful part

// this could be fixed by co-locating allocations on the same page until a request would be too large

// when fixing this: make sure to align on 128 byte boundaries (82599 dma requirement)

if (size % HUGE_PAGE_SIZE) {

size = ((size >> HUGE_PAGE_BITS) + 1) << HUGE_PAGE_BITS;

}

if (require_contiguous && size > HUGE_PAGE_SIZE) {

// this is the place to implement larger contiguous physical mappings if that's ever needed

error("could not map physically contiguous memory");

}

// unique filename, C11 stdatomic.h requires a too recent gcc, we want to support gcc 4.8

uint32_t id = __sync_fetch_and_add(&huge_pg_id, 1);

fs::path path{"/mnt/huge/ixy-" + std::to_string(getpid()) + "-" + std::to_string(id)};

int fd = open(path.c_str(), O_CREAT | O_RDWR, S_IRWXU);

if (fd == -1) {

error("failed to open hugetlbfs file, check that /mnt/huge is mounted");

}

if (ftruncate(fd, static_cast<off_t>(size)) == -1) {

error("failed to allocate huge page memory, check hugetlbfs configuration");

}

void *virt_addr = mmap(nullptr, size, PROT_READ | PROT_WRITE, MAP_SHARED | MAP_HUGETLB, fd, 0);

if (virt_addr == MAP_FAILED) {

error("failed to mmap huge page");

}

// never swap out DMA memory

if (mlock(virt_addr, size) == -1) {

error("disable swap for DMA memory");

}

// don't keep it around in the hugetlbfs

close(fd);

unlink(path.c_str());

return (dma_memory{virt_addr, virt_to_phys(virt_addr)});

}

} // namespace ixy