On 17/07/19 03:13, Wei Yang wrote:
> On Tue, May 14, 2019 at 03:21:08PM +0100, Dr. David Alan Gilbert wrote:
>> * Wei Yang (richardw.y...@linux.intel.com) wrote:
>>> Since start of cpu_physical_memory_sync_dirty_bitmap is always 0, we can
>>> remove this parameter and simplify the calculation a bit.
>>>
>>> Signed-off-by: Wei Yang <richardw.y...@linux.intel.com>
>>
>> So I think you're right it's currently unused; however, lets ask
>> Paolo: Do we need to keep this parameter for flexiblity?
>>
>
> Hey, Paolo
>
> Do you have some spare time to give some insight?
I think it's cleaner to leave the start argument in place. However,
I'll note that in migration_bitmap_sync_range the length argument is
always block->used_length so that's also unnecessary (you already have
block).
Paolo
>> Dave
>>
>>> ---
>>> include/exec/ram_addr.h | 15 ++++++---------
>>> migration/ram.c | 2 +-
>>> 2 files changed, 7 insertions(+), 10 deletions(-)
>>>
>>> diff --git a/include/exec/ram_addr.h b/include/exec/ram_addr.h
>>> index 9ecd911c3e..3dfb2d52fb 100644
>>> --- a/include/exec/ram_addr.h
>>> +++ b/include/exec/ram_addr.h
>>> @@ -409,18 +409,16 @@ static inline void
>>> cpu_physical_memory_clear_dirty_range(ram_addr_t start,
>>>
>>> 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)
>>> {
>>> ram_addr_t addr;
>>> - unsigned long word = BIT_WORD((start + rb->offset) >>
>>> TARGET_PAGE_BITS);
>>> + unsigned long word = BIT_WORD(rb->offset >> TARGET_PAGE_BITS);
>>> uint64_t num_dirty = 0;
>>> unsigned long *dest = rb->bmap;
>>>
>>> - /* start address and length is aligned at the start of a word? */
>>> - if (((word * BITS_PER_LONG) << TARGET_PAGE_BITS) ==
>>> - (start + rb->offset) &&
>>> + /* offset and length is aligned at the start of a word? */
>>> + if (((word * BITS_PER_LONG) << TARGET_PAGE_BITS) == (rb->offset) &&
>>> !(length & ((BITS_PER_LONG << TARGET_PAGE_BITS) - 1))) {
>>> int k;
>>> int nr = BITS_TO_LONGS(length >> TARGET_PAGE_BITS);
>>> @@ -428,14 +426,13 @@ uint64_t
>>> cpu_physical_memory_sync_dirty_bitmap(RAMBlock *rb,
>>> unsigned long idx = (word * BITS_PER_LONG) /
>>> DIRTY_MEMORY_BLOCK_SIZE;
>>> unsigned long offset = BIT_WORD((word * BITS_PER_LONG) %
>>> DIRTY_MEMORY_BLOCK_SIZE);
>>> - unsigned long page = BIT_WORD(start >> TARGET_PAGE_BITS);
>>>
>>> rcu_read_lock();
>>>
>>> src = atomic_rcu_read(
>>> &ram_list.dirty_memory[DIRTY_MEMORY_MIGRATION])->blocks;
>>>
>>> - for (k = page; k < page + nr; k++) {
>>> + for (k = 0; k < nr; k++) {
>>> if (src[idx][offset]) {
>>> unsigned long bits = atomic_xchg(&src[idx][offset], 0);
>>> unsigned long new_dirty;
>>> @@ -458,11 +455,11 @@ uint64_t
>>> cpu_physical_memory_sync_dirty_bitmap(RAMBlock *rb,
>>>
>>> for (addr = 0; addr < length; addr += TARGET_PAGE_SIZE) {
>>> if (cpu_physical_memory_test_and_clear_dirty(
>>> - start + addr + offset,
>>> + addr + offset,
>>> TARGET_PAGE_SIZE,
>>> DIRTY_MEMORY_MIGRATION)) {
>>> *real_dirty_pages += 1;
>>> - long k = (start + addr) >> TARGET_PAGE_BITS;
>>> + long k = addr >> TARGET_PAGE_BITS;
>>> if (!test_and_set_bit(k, dest)) {
>>> num_dirty++;
>>> }
>>> diff --git a/migration/ram.c b/migration/ram.c
>>> index 9948b2d021..1def8122e9 100644
>>> --- a/migration/ram.c
>>> +++ b/migration/ram.c
>>> @@ -1646,7 +1646,7 @@ static void migration_bitmap_sync_range(RAMState *rs,
>>> RAMBlock *rb,
>>> ram_addr_t length)
>>> {
>>> rs->migration_dirty_pages +=
>>> - cpu_physical_memory_sync_dirty_bitmap(rb, 0, length,
>>> + cpu_physical_memory_sync_dirty_bitmap(rb, length,
>>> &rs->num_dirty_pages_period);
>>> }
>>>
>>> --
>>> 2.19.1
>>>
>> --
>> Dr. David Alan Gilbert / dgilb...@redhat.com / Manchester, UK
>
