Re: [Qemu-devel] [PATCH 8/8] Maintain the number of dirty pages

[Orit Wasserman]

On 06/22/2012 04:46 PM, Juan Quintela wrote:
> Calculate the number of dirty pages takes a lot on hosts with lots
> of memory.  Just maintain how many pages are dirty.
> 
> Signed-off-by: Juan Quintela <address@hidden>
> ---
>  arch_init.c     |   15 +--------------
>  cpu-all.h       |    1 +
>  exec-obsolete.h |   10 ++++++++++
>  3 files changed, 12 insertions(+), 14 deletions(-)
> 
> diff --git a/arch_init.c b/arch_init.c
> index 7de1abf..545cf8f 100644
> --- a/arch_init.c
> +++ b/arch_init.c
> @@ -228,20 +228,7 @@ static uint64_t bytes_transferred;
> 
>  static ram_addr_t ram_save_remaining(void)
>  {
> -    RAMBlock *block;
> -    ram_addr_t count = 0;
> -
> -    QLIST_FOREACH(block, &ram_list.blocks, next) {
> -        ram_addr_t addr;
> -        for (addr = 0; addr < block->length; addr += TARGET_PAGE_SIZE) {
> -            if (memory_region_get_dirty(block->mr, addr, TARGET_PAGE_SIZE,
> -                                        DIRTY_MEMORY_MIGRATION)) {
> -                count++;
> -            }
> -        }
> -    }
> -
> -    return count;
> +    return ram_list.dirty_pages;
>  }
> 
>  uint64_t ram_bytes_remaining(void)
> diff --git a/cpu-all.h b/cpu-all.h
> index 50c8b62..88cedba 100644
> --- a/cpu-all.h
> +++ b/cpu-all.h
> @@ -477,6 +477,7 @@ typedef struct RAMBlock {
>  typedef struct RAMList {
>      uint8_t *phys_dirty;
>      QLIST_HEAD(, RAMBlock) blocks;
> +    uint64_t dirty_pages;
>  } RAMList;
>  extern RAMList ram_list;
> 
> diff --git a/exec-obsolete.h b/exec-obsolete.h
> index f8ffce6..c099256 100644
> --- a/exec-obsolete.h
> +++ b/exec-obsolete.h
> @@ -74,6 +74,11 @@ static inline int cpu_physical_memory_get_dirty(ram_addr_t 
> start,
>  static inline int cpu_physical_memory_set_dirty_flags(ram_addr_t addr,
>                                                        int dirty_flags)
>  {
> +    if ((dirty_flags & MIGRATION_DIRTY_FLAG) &&
> +        !cpu_physical_memory_get_dirty(addr, TARGET_PAGE_SIZE,
> +                                       MIGRATION_DIRTY_FLAG)) {
> +        ram_list.dirty_pages++;
> +    }
>      return ram_list.phys_dirty[addr >> TARGET_PAGE_BITS] |= dirty_flags;
>  }
> 
> @@ -87,6 +92,11 @@ static inline int 
> cpu_physical_memory_clear_dirty_flags(ram_addr_t addr,
>  {
>      int mask = ~dirty_flags;
> 
> +    if ((dirty_flags & MIGRATION_DIRTY_FLAG) &&
> +        cpu_physical_memory_get_dirty(addr, TARGET_PAGE_SIZE,
> +                                      MIGRATION_DIRTY_FLAG)) {
> +        ram_list.dirty_pages--;
> +    }
>      return ram_list.phys_dirty[addr >> TARGET_PAGE_BITS] &= mask;
>  }
> 
Reviewed-by: Orit Wasserman <address@hidden>