Re: [Qemu-devel] [PATCH 1/3] exec: store RAMBlock pointer into memory region

[Fam Zheng <famz@redhat.com>]

On Sat, 02/20 10:35, Gonglei wrote:
> Each RAM memory region has a unique corresponding RAMBlock.
> In the current realization, the memory region only stored
> the ram_addr which means the offset of RAM address space,
> We need to qurey the global ram.list to find the ram block
> by ram_addr if we want to get the ram block, which is very
> expensive.
> 
> Now, we store the RAMBlock pointer into memory region
> structure. So, if we know the mr, we can easily get the
> RAMBlock.
> 
> Signed-off-by: Gonglei <arei.gonglei@huawei.com>
> ---
>  exec.c                | 2 ++
>  include/exec/memory.h | 1 +
>  memory.c              | 1 +
>  3 files changed, 4 insertions(+)
> 
> diff --git a/exec.c b/exec.c
> index 1f24500..e29e369 100644
> --- a/exec.c
> +++ b/exec.c
> @@ -1717,6 +1717,8 @@ ram_addr_t qemu_ram_alloc_internal(ram_addr_t size, ram_addr_t max_size,
>          error_propagate(errp, local_err);
>          return -1;
>      }
> +    /* store the ram block pointer into memroy region */

The comment is superfluous IMHO, the code is quite self-explanatory.

> +    mr->ram_block = new_block;
>      return addr;
>  }
>  
> diff --git a/include/exec/memory.h b/include/exec/memory.h
> index c92734a..23e2e3e 100644
> --- a/include/exec/memory.h
> +++ b/include/exec/memory.h
> @@ -172,6 +172,7 @@ struct MemoryRegion {
>      bool global_locking;
>      uint8_t dirty_log_mask;
>      ram_addr_t ram_addr;
> +    void *ram_block;   /* RAMBlock pointer */

Why not add

    typedef struct RAMBlock RAMBlock;

then

    RAMBlock *ram_block;

?

>      Object *owner;
>      const MemoryRegionIOMMUOps *iommu_ops;
>  
> diff --git a/memory.c b/memory.c
> index 09041ed..b4451dd 100644
> --- a/memory.c
> +++ b/memory.c
> @@ -912,6 +912,7 @@ void memory_region_init(MemoryRegion *mr,
>      }
>      mr->name = g_strdup(name);
>      mr->owner = owner;
> +    mr->ram_block = NULL;
>  
>      if (name) {
>          char *escaped_name = memory_region_escape_name(name);
> -- 
> 1.8.5.2
> 
> 
>