Hi Paolo and Jian Zhou,
Do you have any suggestion on this patch?
Thanks,
Keqian
On 2020/6/1 12:02, Keqian Zhu wrote:
> DIRTY_LOG_INITIALLY_ALL_SET feature is on the queue. This fixs the
> dirty rate calculation for this feature. After introducing this
> feature, real_dirty_pages is equal to total memory size at begining.
> This causing wrong dirty rate and false positive throttling.
>
> BTW, real dirty rate is not suitable and not very accurate.
>
> 1. For not suitable: We mainly concern on the relationship between
> dirty rate and network bandwidth. Net increasement of dirty pages
> makes more sense.
> 2. For not very accurate: With manual dirty log clear, some dirty pages
> will be cleared during each peroid, our "real dirty rate" is less
> than real "real dirty rate".
>
> Signed-off-by: Keqian Zhu <zhukeqi...@huawei.com>
> ---
> include/exec/ram_addr.h | 5 ++---
> 1 file changed, 2 insertions(+), 3 deletions(-)
>
> diff --git a/include/exec/ram_addr.h b/include/exec/ram_addr.h
> index 5e59a3d8d7..af9677e291 100644
> --- a/include/exec/ram_addr.h
> +++ b/include/exec/ram_addr.h
> @@ -443,7 +443,7 @@ static inline
> uint64_t cpu_physical_memory_sync_dirty_bitmap(RAMBlock *rb,
> ram_addr_t start,
> ram_addr_t length,
> - uint64_t *real_dirty_pages)
> + uint64_t *accu_dirty_pages)
> {
> ram_addr_t addr;
> unsigned long word = BIT_WORD((start + rb->offset) >> TARGET_PAGE_BITS);
> @@ -469,7 +469,6 @@ uint64_t cpu_physical_memory_sync_dirty_bitmap(RAMBlock
> *rb,
> if (src[idx][offset]) {
> unsigned long bits = atomic_xchg(&src[idx][offset], 0);
> unsigned long new_dirty;
> - *real_dirty_pages += ctpopl(bits);
> new_dirty = ~dest[k];
> dest[k] |= bits;
> new_dirty &= bits;
> @@ -502,7 +501,6 @@ uint64_t cpu_physical_memory_sync_dirty_bitmap(RAMBlock
> *rb,
> start + addr + offset,
> TARGET_PAGE_SIZE,
> DIRTY_MEMORY_MIGRATION)) {
> - *real_dirty_pages += 1;
> long k = (start + addr) >> TARGET_PAGE_BITS;
> if (!test_and_set_bit(k, dest)) {
> num_dirty++;
> @@ -511,6 +509,7 @@ uint64_t cpu_physical_memory_sync_dirty_bitmap(RAMBlock
> *rb,
> }
> }
>
> + *accu_dirty_pages += num_dirty;
> return num_dirty;
> }
> #endif
>
