On Tue, Nov 13, 2018 at 05:54:48PM +0000, Anatoly Burakov wrote:
> When running in no-huge mode, we anonymously allocate our memory.
> While this works for regular NICs and vdev's, it's not suitable
> for memory sharing scenarios such as virtio with vhost_user
> backend.
>
> To fix this, allocate no-huge memory using memfd, and register
> it with memalloc just like any other memseg fd. This will enable
> using rte_memseg_get_fd() API with --no-huge EAL flag.
>
> Signed-off-by: Anatoly Burakov <anatoly.bura...@intel.com>
> ---
> lib/librte_eal/linuxapp/eal/eal_memory.c | 46 ++++++++++++++++++++++--
> 1 file changed, 44 insertions(+), 2 deletions(-)
>
> diff --git a/lib/librte_eal/linuxapp/eal/eal_memory.c
> b/lib/librte_eal/linuxapp/eal/eal_memory.c
> index 48b23ce19..8feac2c56 100644
> --- a/lib/librte_eal/linuxapp/eal/eal_memory.c
> +++ b/lib/librte_eal/linuxapp/eal/eal_memory.c
> @@ -25,6 +25,7 @@
> #include <sys/time.h>
> #include <signal.h>
> #include <setjmp.h>
> +#include <linux/memfd.h>
> #ifdef RTE_EAL_NUMA_AWARE_HUGEPAGES
> #include <numa.h>
> #include <numaif.h>
> @@ -1345,12 +1346,15 @@ eal_legacy_hugepage_init(void)
> /* hugetlbfs can be disabled */
> if (internal_config.no_hugetlbfs) {
> struct rte_memseg_list *msl;
> + int n_segs, cur_seg, fd, memfd, flags;
> uint64_t page_sz;
> - int n_segs, cur_seg;
>
> /* nohuge mode is legacy mode */
> internal_config.legacy_mem = 1;
>
> + /* nohuge mode is single-file segments mode */
> + internal_config.single_file_segments = 1;
> +
> /* create a memseg list */
> msl = &mcfg->memsegs[0];
>
> @@ -1363,8 +1367,36 @@ eal_legacy_hugepage_init(void)
> return -1;
> }
>
> + /* set up parameters for anonymous mmap */
> + fd = -1;
> + flags = MAP_PRIVATE | MAP_ANONYMOUS;
> +
> + /* create a memfd and store it in the segment fd table */
> + memfd = memfd_create("nohuge", 0);
> + if (memfd < 0) {
> + RTE_LOG(ERR, EAL, "Cannot create memfd: %s\n",
> + strerror(errno));
> + RTE_LOG(ERR, EAL, "Falling back to anonymous map\n");
> + } else {
> + /* we got an fd - now resize it */
> + if (ftruncate(memfd, internal_config.memory) < 0) {
> + RTE_LOG(ERR, EAL, "Cannot resize memfd: %s\n",
> + strerror(errno));
> + RTE_LOG(ERR, EAL, "Falling back to anonymous
> map\n");
> + close(memfd);
> + } else {
> + /* creating memfd-backed file was successful.
> + * we want changes to memfd to be visible to
> + * other processes (such as vhost backend), so
> + * map it as shared memory.
> + */
> + RTE_LOG(DEBUG, EAL, "Using memfd for anonymous
> memory\n");
> + fd = memfd;
> + flags = MAP_SHARED;
> + }
> + }
> addr = mmap(NULL, internal_config.memory, PROT_READ |
> PROT_WRITE,
> - MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
> + flags, fd, 0);
> if (addr == MAP_FAILED) {
> RTE_LOG(ERR, EAL, "%s: mmap() failed: %s\n", __func__,
> strerror(errno));
> @@ -1375,6 +1407,16 @@ eal_legacy_hugepage_init(void)
> msl->socket_id = 0;
> msl->len = internal_config.memory;
>
> + /* we're in single-file segments mode, so only the segment list
> + * fd needs to be set up.
> + */
> + if (fd != -1) {
> + if (eal_memalloc_set_seg_list_fd(0, fd) < 0) {
> + RTE_LOG(ERR, EAL, "Cannot set up segment list
> fd\n");
> + /* not a serious error, proceed */
> + }
> + }
Hi Anatoly,
Thanks for the work!
It seems the support for getting fd offset is missing in no-huge
mode. I got below error in virtio-user while trying this series
with --no-huge:
update_memory_region(): Failed to get offset, ms=0x10002e000 rte_errno=19
Thanks
> +
> /* populate memsegs. each memseg is one page long */
> for (cur_seg = 0; cur_seg < n_segs; cur_seg++) {
> arr = &msl->memseg_arr;
> --
> 2.17.1
