* Gonglei (Arei) (arei.gong...@huawei.com) wrote:
> Reducing data copy can reduce cpu overheah.
(Note a few typos in subject/title)
> Signed-off-by: ChenLiang <chenlian...@huawei.com>
> Signed-off-by: Gonglei <arei.gong...@huawei.com>
> ---
> arch_init.c | 8 +++-----
> 1 file changed, 3 insertions(+), 5 deletions(-)
>
> diff --git a/arch_init.c b/arch_init.c
> index 2211e0b..cc88875 100644
> --- a/arch_init.c
> +++ b/arch_init.c
> @@ -344,11 +344,8 @@ static int save_xbzrle_page(QEMUFile *f, uint8_t
> **current_data,
>
> prev_cached_page = get_cached_data(XBZRLE.cache, current_addr);
>
> - /* save current buffer into memory */
> - memcpy(XBZRLE.current_buf, *current_data, TARGET_PAGE_SIZE);
> -
> /* XBZRLE encoding (if there is no overflow) */
> - encoded_len = xbzrle_encode_buffer(prev_cached_page, XBZRLE.current_buf,
> + encoded_len = xbzrle_encode_buffer(prev_cached_page, *current_data,
> TARGET_PAGE_SIZE, XBZRLE.encoded_buf,
> TARGET_PAGE_SIZE);
Is xbzrle_encode_buffer safe if the main memory is still being changed while
it is run? Even with multiple CPUs changing it? Even on CPUs with looser
memory ordering semantics?
> if (encoded_len == 0) {
> @@ -367,7 +364,8 @@ static int save_xbzrle_page(QEMUFile *f, uint8_t
> **current_data,
>
> /* we need to update the data in the cache, in order to get the same
> data */
> if (!last_stage) {
> - memcpy(prev_cached_page, XBZRLE.current_buf, TARGET_PAGE_SIZE);
> + xbzrle_decode_buffer(XBZRLE.encoded_buf, encoded_len,
> prev_cached_page,
> +
> TARGET_PAGE_SIZE);
> }
>
> /* Send XBZRLE based compressed page */
> --
> 1.7.12.4
>
>
> Best regards,
> -Gonglei
>
>
--
Dr. David Alan Gilbert / dgilb...@redhat.com / Manchester, UK
