Re: [Qemu-devel] [PATCH 37/38] migration: synchronize memory bitmap 64bits at a time

[Orit Wasserman <owasserm@redhat.com>]

On 12/17/2013 05:26 PM, Juan Quintela wrote:
> We use the old code if the bitmaps are not aligned
>
> Signed-off-by: Juan Quintela <quintela@redhat.com>
> ---
>   arch_init.c | 38 +++++++++++++++++++++++++++++---------
>   1 file changed, 29 insertions(+), 9 deletions(-)
>
> diff --git a/arch_init.c b/arch_init.c
> index 2cd3d00..77912e7 100644
> --- a/arch_init.c
> +++ b/arch_init.c
> @@ -50,6 +50,7 @@
>   #include "exec/cpu-all.h"
>   #include "exec/ram_addr.h"
>   #include "hw/acpi/acpi.h"
> +#include "qemu/host-utils.h"
>
>   #ifdef DEBUG_ARCH_INIT
>   #define DPRINTF(fmt, ...) \
> @@ -376,15 +377,34 @@ static inline bool migration_bitmap_set_dirty(ram_addr_t addr)
>   static void migration_bitmap_sync_range(ram_addr_t start, ram_addr_t length)
>   {
>       ram_addr_t addr;
> -
> -    for (addr = 0; addr < length; addr += TARGET_PAGE_SIZE) {
> -        if (cpu_physical_memory_get_dirty(start + addr,
> -                                          TARGET_PAGE_SIZE,
> -                                          DIRTY_MEMORY_MIGRATION)) {
> -            cpu_physical_memory_reset_dirty(start + addr,
> -                                            TARGET_PAGE_SIZE,
> -                                            DIRTY_MEMORY_MIGRATION);
> -            migration_bitmap_set_dirty(start + addr);
> +    unsigned long page = BIT_WORD(start >> TARGET_PAGE_BITS);
> +
> +    /* start address is aligned at the start of a word? */
> +    if (((page * BITS_PER_LONG) << TARGET_PAGE_BITS) == start) {
> +        int k;
> +        int nr = BITS_TO_LONGS(length >> TARGET_PAGE_BITS);
> +        unsigned long *src = ram_list.dirty_memory[DIRTY_MEMORY_MIGRATION];
> +
> +        for (k = page; k < page + nr; k++) {
> +            if (src[k]) {
> +                unsigned long new_dirty;
> +                new_dirty = ~migration_bitmap[k];
> +                migration_bitmap[k] |= src[k];
> +                new_dirty &= src[k];
> +                migration_dirty_pages += ctpopl(new_dirty);
> +                src[k] = 0;
> +            }
> +        }
> +    } else {
> +        for (addr = 0; addr < length; addr += TARGET_PAGE_SIZE) {
> +            if (cpu_physical_memory_get_dirty(start + addr,
> +                                              TARGET_PAGE_SIZE,
> +                                              DIRTY_MEMORY_MIGRATION)) {
> +                cpu_physical_memory_reset_dirty(start + addr,
> +                                                TARGET_PAGE_SIZE,
> +                                                DIRTY_MEMORY_MIGRATION);
> +                migration_bitmap_set_dirty(start + addr);
> +            }
>           }
>       }
>   }
>

Reviewed-by: Orit Wasserman <owasserm@redhat.com>