[dpdk-dev] [PATCH 4/4] vhost: avoid populate guest memory
Maxime Coquelin
maxime.coquelin at redhat.com
Mon Feb 19 21:44:49 CET 2018
Hi Jianfeng,
On 02/14/2018 05:01 AM, Jianfeng Tan wrote:
> It's not necessary to polulate guest memory from vhost side.
>
> Cc: maxime.coquelin at redhat.com
> Cc: yliu at fridaylinux.org
>
> Signed-off-by: Jianfeng Tan <jianfeng.tan at intel.com>
> ---
> lib/librte_vhost/vhost_user.c | 4 +++-
> 1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/lib/librte_vhost/vhost_user.c b/lib/librte_vhost/vhost_user.c
> index 90ed211..9bd0391 100644
> --- a/lib/librte_vhost/vhost_user.c
> +++ b/lib/librte_vhost/vhost_user.c
> @@ -644,6 +644,7 @@ vhost_user_set_mem_table(struct virtio_net *dev, struct VhostUserMsg *pmsg)
> uint64_t mmap_offset;
> uint64_t alignment;
> uint32_t i;
> + int populate;
> int fd;
>
> if (dev->mem && !vhost_memory_changed(&memory, dev->mem)) {
> @@ -714,8 +715,9 @@ vhost_user_set_mem_table(struct virtio_net *dev, struct VhostUserMsg *pmsg)
> }
> mmap_size = RTE_ALIGN_CEIL(mmap_size, alignment);
>
> + populate = (dev->dequeue_zero_copy) ? MAP_POPULATE : 0;
> mmap_addr = mmap(NULL, mmap_size, PROT_READ | PROT_WRITE,
> - MAP_SHARED | MAP_POPULATE, fd, 0);
> + MAP_SHARED | populate, fd, 0);
>
> if (mmap_addr == MAP_FAILED) {
> RTE_LOG(ERR, VHOST_CONFIG,
>
Wouldn't not populating all the guest memory have a bad impact on 0%
acceptable loss use-cases?
Thanks,
Maxime
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