"Dr. David Alan Gilbert (git)" <dgilb...@redhat.com> wrote:
> From: "Dr. David Alan Gilbert" <dgilb...@redhat.com>
>
> Unfortunately madvise DONTNEED doesn't work on hugepagetlb
> so use fallocate(FALLOC_FL_PUNCH_HOLE)
> qemu_fd_getpagesize only sets the page based off a file
> if the file is from hugetlbfs.
>
> Signed-off-by: Dr. David Alan Gilbert <dgilb...@redhat.com>
Reviewed-by: Juan Quintela <quint...@redhat.com>
But ...
> ---
> exec.c | 13 ++++++++++++-
> 1 file changed, 12 insertions(+), 1 deletion(-)
>
> diff --git a/exec.c b/exec.c
> index e040cdf..c25f6b3 100644
> --- a/exec.c
> +++ b/exec.c
> @@ -3324,9 +3324,20 @@ int ram_block_discard_range(RAMBlock *rb, uint64_t
> start, size_t length)
>
> errno = ENOTSUP; /* If we are missing MADVISE etc */
>
> + if (rb->page_size == qemu_host_page_size) {
> #if defined(CONFIG_MADVISE)
> - ret = qemu_madvise(host_startaddr, length, QEMU_MADV_DONTNEED);
> + ret = qemu_madvise(host_startaddr, length, QEMU_MADV_DONTNEED);
> #endif
> + } else {
> + /* Huge page case - unfortunately it can't do DONTNEED, but
> + * it can do the equivalent by FALLOC_FL_PUNCH_HOLE in the
> + * huge page file.
> + */
> +#ifdef CONFIG_FALLOCATE_PUNCH_HOLE
> + ret = fallocate(rb->fd, FALLOC_FL_PUNCH_HOLE |
> FALLOC_FL_KEEP_SIZE,
> + start, length);
Why can't we use fallocate() when !CONFIG_MADVISE?
or even ...
if (rb->page_size == qemu_host_page_size) {
#if defined(CONFIG_MADVISE)
ret = qemu_madvise(host_startaddr, length, QEMU_MADV_DONTNEED);
#endif
}
if (ret == -1) {
/* Huge page case - unfortunately it can't do DONTNEED, but
* it can do the equivalent by FALLOC_FL_PUNCH_HOLE in the
* huge page file.
*/
#ifdef CONFIG_FALLOCATE_PUNCH_HOLE
ret = fallocate(rb->fd, FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE,
start, length);
#endif
}
