Re: [PATCH 4/6] migration/postcopy: set all_zero to true on the first target page

From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
To: Wei Yang <richardw.yang@linux.intel.com>
Cc: qemu-devel@nongnu.org, quintela@redhat.com
Subject: Re: [PATCH 4/6] migration/postcopy: set all_zero to true on the first target page
Date: Wed, 6 Nov 2019 20:04:58 +0000	[thread overview]
Message-ID: <20191106200458.GK2802@work-vm> (raw)
In-Reply-To: <20191018004850.9888-5-richardw.yang@linux.intel.com>

* Wei Yang (richardw.yang@linux.intel.com) wrote:
> For the first target page, all_zero is set to true for this round check.
> 
> After target_pages introduced, we could leverage this variable instead
> of checking the address offset.
> 
> Signed-off-by: Wei Yang <richardw.yang@linux.intel.com>

Yes, OK - I find target_pages being incremented before
this point a bit confusing, I think of '0' as the first one.

Still, it's OK:

Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>

> ---
>  migration/ram.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/migration/ram.c b/migration/ram.c
> index 5c05376d8d..b5759793a9 100644
> --- a/migration/ram.c
> +++ b/migration/ram.c
> @@ -4067,7 +4067,7 @@ static int ram_load_postcopy(QEMUFile *f)
>              page_buffer = postcopy_host_page +
>                            ((uintptr_t)host & (block->page_size - 1));
>              /* If all TP are zero then we can optimise the place */
> -            if (!((uintptr_t)host & (block->page_size - 1))) {
> +            if (target_pages == 1) {
>                  all_zero = true;
>              } else {
>                  /* not the 1st TP within the HP */
> -- 
> 2.17.1
> 
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK