On 3/12/21 1:03 PM, leirao wrote:
> From: "Rao, Lei" <[email protected]>
>
> When flushing memory from ram cache to ram during every checkpoint
> on secondary VM, we can copy continuous chunks of memory instead of
> 4096 bytes per time to reduce the time of VM stop during checkpoint.
>
> Signed-off-by: Lei Rao <[email protected]>
> ---
> migration/ram.c | 44 +++++++++++++++++++++++++++++++++++++++++---
> 1 file changed, 41 insertions(+), 3 deletions(-)
>
> diff --git a/migration/ram.c b/migration/ram.c
> index e795a8d..b269637 100644
> --- a/migration/ram.c
> +++ b/migration/ram.c
> @@ -823,6 +823,39 @@ unsigned long migration_bitmap_find_dirty(RAMState *rs,
> RAMBlock *rb,
> return next;
> }
>
> +/*
> + * colo_bitmap_find_diry:find contiguous dirty pages from start
> + *
> + * Returns the page offset within memory region of the start of the
> contiguout
> + * dirty page
> + *
> + * @rs: current RAM state
> + * @rb: RAMBlock where to search for dirty pages
> + * @start: page where we start the search
> + * @num: the number of contiguous dirty pages
> + */
> +static inline
> +unsigned long colo_bitmap_find_dirty(RAMState *rs, RAMBlock *rb,
> + unsigned long start, unsigned long *num)
> +{
> + unsigned long size = rb->used_length >> TARGET_PAGE_BITS;
> + unsigned long *bitmap = rb->bmap;
> + unsigned long first, next;
> +
> + if (ramblock_is_ignored(rb)) {
> + return size;
> + }
> +
> + first = find_next_bit(bitmap, size, start);
> + if (first >= size) {
> + return first;
> + }
> + next = find_next_zero_bit(bitmap, size, first + 1);
> + assert(next >= first);
> + *num = next - first;
> + return first;
The idea is outstanding
i wonder it should return (next - 1) ?
Thanks
Zhijian
> +}
> +
> static inline bool migration_bitmap_clear_dirty(RAMState *rs,
> RAMBlock *rb,
> unsigned long page)
> @@ -3669,6 +3702,8 @@ void colo_flush_ram_cache(void)
> void *dst_host;
> void *src_host;
> unsigned long offset = 0;
> + unsigned long num = 0;
> + unsigned long i = 0;
>
> memory_global_dirty_log_sync();
> WITH_RCU_READ_LOCK_GUARD() {
> @@ -3682,19 +3717,22 @@ void colo_flush_ram_cache(void)
> block = QLIST_FIRST_RCU(&ram_list.blocks);
>
> while (block) {
> - offset = migration_bitmap_find_dirty(ram_state, block, offset);
> + offset = colo_bitmap_find_dirty(ram_state, block, offset, &num);
>
> if (((ram_addr_t)offset) << TARGET_PAGE_BITS
> >= block->used_length) {
> offset = 0;
> + num = 0;
> block = QLIST_NEXT_RCU(block, next);
> } else {
> - migration_bitmap_clear_dirty(ram_state, block, offset);
> + for (i = 0; i < num; i++) {
> + migration_bitmap_clear_dirty(ram_state, block, offset +
> i);
> + }
> dst_host = block->host
> + (((ram_addr_t)offset) << TARGET_PAGE_BITS);
> src_host = block->colo_cache
> + (((ram_addr_t)offset) << TARGET_PAGE_BITS);
> - memcpy(dst_host, src_host, TARGET_PAGE_SIZE);
> + memcpy(dst_host, src_host, TARGET_PAGE_SIZE * num);
> }
> }
> }
