On 02/05/2010 12:18 PM, OHMURA Kei wrote:
> dirty-bitmap-traveling is carried out by byte size in qemu-kvm.c.
> But We think that dirty-bitmap-traveling by long size is faster than by byte
> size especially when most of memory is not dirty.
>
>
>
> +
> +static int kvm_get_dirty_pages_log_range_by_long(unsigned long start_addr,
> + unsigned char *bitmap,
> + unsigned long offset,
> + unsigned long mem_size)
> +{
> + unsigned int i;
> + unsigned int len;
> + unsigned long *bitmap_ul = (unsigned long *)bitmap;
> +
> + /* bitmap-traveling by long size is faster than by byte size
> + * especially when most of memory is not dirty.
> + * bitmap should be long-size aligned for traveling by long.
> + */
> + if (((unsigned long)bitmap & (TARGET_LONG_SIZE - 1)) == 0) {
>
Since we allocate the bitmap, we can be sure that it is aligned on a
long boundary (qemu_malloc() should guarantee that). So you can
eliminate the fallback.
> + len = ((mem_size / TARGET_PAGE_SIZE) + TARGET_LONG_BITS - 1) /
> + TARGET_LONG_BITS;
> + for (i = 0; i < len; i++)
> + if (bitmap_ul[i] != 0)
> + kvm_get_dirty_pages_log_range_by_byte(i * TARGET_LONG_SIZE,
> + (i + 1) * TARGET_LONG_SIZE, bitmap, offset);
>
Better to just use the original loop here (since we don't need the
function as a fallback).
> + /*
> + * We will check the remaining dirty-bitmap,
> + * when the mem_size is not a multiple of TARGET_LONG_SIZE.
> + */
> + if ((mem_size & (TARGET_LONG_SIZE - 1)) != 0) {
> + len = ((mem_size / TARGET_PAGE_SIZE) + 7) / 8;
> + kvm_get_dirty_pages_log_range_by_byte(i * TARGET_LONG_SIZE,
> + len, bitmap, offset);
> + }
>
Seems like the bitmap size is also aligned as well (allocated using
BITMAP_SIZE which aligns using HOST_LONG_BITS), so this is unnecessary
as well.
--
error compiling committee.c: too many arguments to function
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