Re: [Qemu-devel] [PATCHv2 8/9] migration: do not search dirty pages in bulk stage

[Eric Blake]

On 03/15/2013 09:50 AM, Peter Lieven wrote:
> avoid searching for dirty pages just increment the
> page offset. all pages are dirty anyway.
> 
> Signed-off-by: Peter Lieven <address@hidden>
> ---
>  arch_init.c |   12 +++++++++---
>  1 file changed, 9 insertions(+), 3 deletions(-)

> 
> diff --git a/arch_init.c b/arch_init.c
> index a3dc20d..ca281ad 100644
> --- a/arch_init.c
> +++ b/arch_init.c
> @@ -321,8 +321,14 @@ ram_addr_t 
> migration_bitmap_find_and_reset_dirty(MemoryRegion *mr,
>      unsigned long nr = base + (start >> TARGET_PAGE_BITS);
>      unsigned long size = base + (int128_get64(mr->size) >> TARGET_PAGE_BITS);
>  
> -    unsigned long next = find_next_bit(migration_bitmap, size, nr);
> -
> +    unsigned long next;
> +    
> +    if (ram_bulk_stage) {
> +        next = nr + 1;
> +    } else {
> +        next = find_next_bit(migration_bitmap, size, nr);
> +    }

This part makes sense.

> +    
>      if (next < size) {
>          clear_bit(next, migration_bitmap);
>          migration_dirty_pages--;
> @@ -523,7 +529,7 @@ static void reset_ram_globals(void)
>  {
>      last_seen_block = NULL;
>      last_sent_block = NULL;
> -    last_offset = 0;
> +    last_offset = -1;

But what is this change doing?  I don't see it mentioned in the commit
message.  Does it belong to a different commit?

>      last_version = ram_list.version;
>      ram_bulk_stage = true;
>  }
> 

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org

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