* guangrong.xiao@xxxxxxxxx (guangrong.xiao@xxxxxxxxx) wrote:
> From: Xiao Guangrong <xiaoguangrong@xxxxxxxxxxx>
>
> save_zero_page() is always our first approach to try, move it to
> the common place before calling ram_save_compressed_page
> and ram_save_page
>
> Signed-off-by: Xiao Guangrong <xiaoguangrong@xxxxxxxxxxx>
> ---
> migration/ram.c | 106 ++++++++++++++++++++++++++++++++------------------------
> 1 file changed, 60 insertions(+), 46 deletions(-)
>
> diff --git a/migration/ram.c b/migration/ram.c
> index 839665d866..9627ce18e9 100644
> --- a/migration/ram.c
> +++ b/migration/ram.c
> @@ -1021,15 +1021,8 @@ static int ram_save_page(RAMState *rs, PageSearchStatus *pss, bool last_stage)
> trace_ram_save_page(block->idstr, (uint64_t)offset, p);
>
> XBZRLE_cache_lock();
> - pages = save_zero_page(rs, block, offset);
> - if (pages > 0) {
> - /* Must let xbzrle know, otherwise a previous (now 0'd) cached
> - * page would be stale
> - */
> - xbzrle_cache_zero_page(rs, current_addr);
> - ram_release_pages(block->idstr, offset, pages);
> - } else if (!rs->ram_bulk_stage &&
> - !migration_in_postcopy() && migrate_use_xbzrle()) {
> + if (!rs->ram_bulk_stage && !migration_in_postcopy() &&
> + migrate_use_xbzrle()) {
> pages = save_xbzrle_page(rs, &p, current_addr, block,
> offset, last_stage);
> if (!last_stage) {
> @@ -1172,40 +1165,23 @@ static int ram_save_compressed_page(RAMState *rs, PageSearchStatus *pss,
>
> p = block->host + offset;
>
> - /* When starting the process of a new block, the first page of
> - * the block should be sent out before other pages in the same
> - * block, and all the pages in last block should have been sent
> - * out, keeping this order is important, because the 'cont' flag
> - * is used to avoid resending the block name.
> - */
> if (block != rs->last_sent_block) {
> - flush_compressed_data(rs);
> - pages = save_zero_page(rs, block, offset);
> - 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;
> - }
> + /*
> + * 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;
> } else {
> - pages = save_zero_page(rs, block, offset);
> - if (pages == -1) {
> - pages = compress_page_with_multi_thread(rs, block, offset);
> - } else {
> - ram_release_pages(block->idstr, offset, pages);
> - }
> + pages = compress_page_with_multi_thread(rs, block, offset);
> }
>
> return pages;
> @@ -1447,6 +1423,25 @@ err:
> return -1;
> }
>
> +static bool save_page_use_compression(RAMState *rs)
> +{
> + if (!migrate_use_compression()) {
> + return false;
> + }
> +
> + /*
> + * If xbzrle is on, stop using the data compression after first
> + * round of migration even if compression is enabled. In theory,
> + * xbzrle can do better than compression.
> + */
> + if (rs->ram_bulk_stage || !migrate_use_xbzrle()) {
> + return true;
> + }
> +
> + return false;
> +
> +}
> +
> /**
> * ram_save_target_page: save one target page
> *
> @@ -1472,12 +1467,31 @@ static int ram_save_target_page(RAMState *rs, PageSearchStatus *pss,
> }
>
> /*
> - * If xbzrle is on, stop using the data compression after first
> - * round of migration even if compression is enabled. In theory,
> - * xbzrle can do better than compression.
> + * When starting the process of a new block, the first page of
> + * the block should be sent out before other pages in the same
> + * block, and all the pages in last block should have been sent
> + * out, keeping this order is important, because the 'cont' flag
> + * is used to avoid resending the block name.
> */
> - if (migrate_use_compression() &&
> - (rs->ram_bulk_stage || !migrate_use_xbzrle())) {
> + if (block != rs->last_sent_block && save_page_use_compression(rs)) {
> + flush_compressed_data(rs);
> + }
> +
> + res = save_zero_page(rs, block, offset);
> + if (res > 0) {
> + /* Must let xbzrle know, otherwise a previous (now 0'd) cached
> + * page would be stale
> + */
> + if (!save_page_use_compression(rs)) {
This test is quite interesting; I think the
reason it's different in the compression case is that since we don't put
any none-0 data in the xbzrle cache, we don't need to knock any old
none-0 pages out of the cache.
> + XBZRLE_cache_lock();
> + xbzrle_cache_zero_page(rs, block->offset + offset);
> + XBZRLE_cache_unlock();
> + }
> + ram_release_pages(block->idstr, offset, res);
> + goto page_saved;
> + }
> +
> + if (save_page_use_compression(rs)) {
> res = ram_save_compressed_page(rs, pss, last_stage);
> } else {
> res = ram_save_page(rs, pss, last_stage);
Reviewed-by: Dr. David Alan Gilbert <dgilbert@xxxxxxxxxx>
> --
> 2.14.3
>
>
--
Dr. David Alan Gilbert / dgilbert@xxxxxxxxxx / Manchester, UK
