Re: [Qemu-devel] [PATCHv2 1/2] Revert "migration: do not sent zero pages in bulk stage"

[mdroth <mdroth@linux.vnet.ibm.com>]

On Mon, Jun 10, 2013 at 12:14:19PM +0200, Peter Lieven wrote:
> Not sending zero pages breaks migration if a page is zero
> at the source but not at the destination. This can e.g. happen
> if different BIOS versions are used at source and destination.
> It has also been reported that migration on pseries is completely
> broken with this patch.
> 
> This effectively reverts commit f1c72795af573b24a7da5eb52375c9aba8a37972.
> 
> Conflicts:
> 
> 	arch_init.c
> 
> Signed-off-by: Peter Lieven <pl@kamp.de>

Reviewed-by: Michael Roth <mdroth@linux.vnet.ibm.com>

Also CC'ing qemu-stable

> ---
>  arch_init.c |   13 ++++---------
>  1 file changed, 4 insertions(+), 9 deletions(-)
> 
> diff --git a/arch_init.c b/arch_init.c
> index 5d32ecf..08fccf6 100644
> --- a/arch_init.c
> +++ b/arch_init.c
> @@ -457,15 +457,10 @@ static int ram_save_block(QEMUFile *f, bool last_stage)
>              bytes_sent = -1;
>              if (is_zero_page(p)) {
>                  acct_info.dup_pages++;
> -                if (!ram_bulk_stage) {
> -                    bytes_sent = save_block_hdr(f, block, offset, cont,
> -                                                RAM_SAVE_FLAG_COMPRESS);
> -                    qemu_put_byte(f, 0);
> -                    bytes_sent++;
> -                } else {
> -                    acct_info.skipped_pages++;
> -                    bytes_sent = 0;
> -                }
> +                bytes_sent = save_block_hdr(f, block, offset, cont,
> +                                            RAM_SAVE_FLAG_COMPRESS);
> +                qemu_put_byte(f, 0);
> +                bytes_sent++;
>              } else if (!ram_bulk_stage && migrate_use_xbzrle()) {
>                  current_addr = block->offset + offset;
>                  bytes_sent = save_xbzrle_page(f, p, current_addr, block,
> -- 
> 1.7.9.5
> 
>