Re: [Qemu-devel] [PATCH 2/2] find_ram_offset: Align ram_addr_t allocation on long boundaries

[Eric Blake]

On 01/05/2018 11:01 AM, Dr. David Alan Gilbert (git) wrote:
> From: "Dr. David Alan Gilbert" <address@hidden>
> 
> The dirty bitmaps are built from 'long'sand there is fast-path code

s/'long'sand/'long's, and/

> for synchronising the case where the RAMBlock is aligned to the start
> of a long boundary.  Align the allocation to this boundary
> to cause the fast path to be used.
> 

> Suggested-by: Paolo Bonzini <address@hidden>
> Signed-off-by: Dr. David Alan Gilbert <address@hidden>
> ---
>  exec.c | 5 +++++
>  1 file changed, 5 insertions(+)

Reviewed-by: Eric Blake <address@hidden>

> 
> diff --git a/exec.c b/exec.c
> index 7966570231..644603f05e 100644
> --- a/exec.c
> +++ b/exec.c
> @@ -1694,6 +1694,11 @@ static ram_addr_t find_ram_offset(ram_addr_t size)
>              }
>          }
>  
> +        /* Align blocks to start on a 'long' in the bitmap
> +         * which makes the bitmap sync'ing take the fast path.
> +         */
> +        end = ROUND_UP(end, BITS_PER_LONG << TARGET_PAGE_BITS);
> +
>          /* If it fits remember our place and remember the size
>           * of gap, but keep going so that we might find a smaller
>           * gap to fill so avoiding fragmentation.
> 

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3266
Virtualization:  qemu.org | libvirt.org

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