[dpdk-dev] vhost-user technical isssues

[Tetsuya Mukawa]

(2014/11/14 12:40), Tetsuya Mukawa wrote:
> I am using 1GB hugepage size.
>
> $ sudo QTEST_HUGETLBFS_PATH=/mnt/huge make check
> region=0, mmap=0x2aaac0000000, size=6291456000
> region=0, munmap=0x2aaac0000000, size=6291456000, ret=-1 << failed
>
> 6291456000 is not aligned by 1GB.
> When I specify 4096MB as guest memory size, munmap() doesn't return
> error like following.
>
> $ sudo QTEST_HUGETLBFS_PATH=/mnt/huge make check
> region=0, mmap=0x2aaac0000000, size=4294967296
> region=0, munmap=0x2aaac0000000, size=4294967296, ret=0
>
>
Also I've checked mmap2 and munmap implementation of current linux kernel.
When a file on hugetlbfs is mapped, 'size' will be aligned by hugepages
size in some case.
But when munmap is called, 'size' will be aligned by PAGE_SIZE.
It mean we cannot use same 'size' value for mmap and munmap in some case.
I guess this implementation or specification cases the munmap issue.

Thanks,
Tetsuya