[dpdk-dev] [PATCH 2/3] net/virtio-user: avoid parsing process mappings
Burakov, Anatoly
anatoly.burakov at intel.com
Fri Sep 7 11:39:16 CEST 2018
On 05-Sep-18 5:28 AM, Tiwei Bie wrote:
> Recently some memory APIs were introduced to allow users to
> get the file descriptor and offset for each memory segment.
> We can leverage those APIs to get rid of the /proc magic on
> memory table preparation in vhost-user backend.
>
> Signed-off-by: Tiwei Bie <tiwei.bie at intel.com>
> ---
<snip>
> - for (i = 0; i < num; ++i) {
> - mr = &msg->payload.memory.regions[i];
> - mr->guest_phys_addr = huges[i].addr; /* use vaddr! */
> - mr->userspace_addr = huges[i].addr;
> - mr->memory_size = huges[i].size;
> - mr->mmap_offset = 0;
> - fds[i] = open(huges[i].path, O_RDWR);
> + if (rte_memseg_get_fd_offset_thread_unsafe(ms, &offset) < 0) {
> + PMD_DRV_LOG(ERR, "Failed to get offset, ms=%p rte_errno=%d",
> + ms, rte_errno);
> + return -1;
> + }
> +
> + start_addr = (uint64_t)(uintptr_t)ms->addr;
> + end_addr = start_addr + ms->len;
> +
> + for (i = 0; i < wa->region_nr; i++) {
There has to be a better way than to run this loop on every segment.
Maybe store last-used region, and only do a region look up if there's a
mismatch? Generally, in single-file segments mode, you'll get lots of
segments from one memseg list one after the other, so you will need to
do a lookup once memseg list changes, instead of on each segment.
> + if (wa->fds[i] != fd)
> + continue;
> +
> + mr = &wa->vm->regions[i];
> +
> + if (mr->userspace_addr + mr->memory_size < end_addr)
> + mr->memory_size = end_addr - mr->userspace_addr;
> +
<snip>
> int fds[VHOST_MEMORY_MAX_NREGIONS];
> int fd_num = 0;
> - int i, len;
> + int len;
> int vhostfd = dev->vhostfd;
>
> RTE_SET_USED(m);
> @@ -364,10 +337,6 @@ vhost_user_sock(struct virtio_user_dev *dev,
> return -1;
> }
>
> - if (req == VHOST_USER_SET_MEM_TABLE)
> - for (i = 0; i < fd_num; ++i)
> - close(fds[i]);
> -
You're sharing fd's - presumably the other side of this is in a
different process, so it's safe to close these fd's there?
> if (need_reply) {
> if (vhost_user_read(vhostfd, &msg) < 0) {
> PMD_DRV_LOG(ERR, "Received msg failed: %s",
>
--
Thanks,
Anatoly
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