* guangrong.xiao@xxxxxxxxx (guangrong.xiao@xxxxxxxxx) wrote:
> From: Xiao Guangrong <xiaoguangrong@xxxxxxxxxxx>
>
> As compression is a heavy work, do not do it in migration thread,
> instead, we post it out as a normal page
>
> Signed-off-by: Xiao Guangrong <xiaoguangrong@xxxxxxxxxxx>
> ---
> migration/ram.c | 32 ++++++++++++++++----------------
Hi,
Do you have some performance numbers to show this helps? Were those
taken on a normal system or were they taken with one of the compression
accelerators (which I think the compression migration was designed for)?
> 1 file changed, 16 insertions(+), 16 deletions(-)
>
> diff --git a/migration/ram.c b/migration/ram.c
> index 7266351fd0..615693f180 100644
> --- a/migration/ram.c
> +++ b/migration/ram.c
> @@ -1132,7 +1132,7 @@ static int ram_save_compressed_page(RAMState *rs, PageSearchStatus *pss,
> int pages = -1;
> uint64_t bytes_xmit = 0;
> uint8_t *p;
> - int ret, blen;
> + int ret;
> RAMBlock *block = pss->block;
> ram_addr_t offset = pss->page << TARGET_PAGE_BITS;
>
> @@ -1162,23 +1162,23 @@ static int ram_save_compressed_page(RAMState *rs, PageSearchStatus *pss,
> if (block != rs->last_sent_block) {
> flush_compressed_data(rs);
> pages = save_zero_page(rs, block, offset);
> - if (pages == -1) {
> - /* Make sure the first page is sent out before other pages */
> - bytes_xmit = save_page_header(rs, rs->f, block, offset |
> - RAM_SAVE_FLAG_COMPRESS_PAGE);
> - blen = qemu_put_compression_data(rs->f, p, TARGET_PAGE_SIZE,
> - migrate_compress_level());
> - if (blen > 0) {
> - ram_counters.transferred += bytes_xmit + blen;
> - ram_counters.normal++;
> - pages = 1;
> - } else {
> - qemu_file_set_error(rs->f, blen);
> - error_report("compressed data failed!");
> - }
> - }
> if (pages > 0) {
> ram_release_pages(block->idstr, offset, pages);
> + } else {
> + /*
> + * Make sure the first page is sent out before other pages.
> + *
> + * we post it as normal page as compression will take much
> + * CPU resource.
> + */
> + ram_counters.transferred += save_page_header(rs, rs->f, block,
> + offset | RAM_SAVE_FLAG_PAGE);
> + qemu_put_buffer_async(rs->f, p, TARGET_PAGE_SIZE,
> + migrate_release_ram() &
> + migration_in_postcopy());
> + ram_counters.transferred += TARGET_PAGE_SIZE;
> + ram_counters.normal++;
> + pages = 1;
However, the code and idea look OK, so
Reviewed-by: Dr. David Alan Gilbert <dgilbert@xxxxxxxxxx>
> }
> } else {
> pages = save_zero_page(rs, block, offset);
> --
> 2.14.3
>
>
--
Dr. David Alan Gilbert / dgilbert@xxxxxxxxxx / Manchester, UK
