Commit fb613580 authored by Keqian Zhu's avatar Keqian Zhu Committed by Dr. David Alan Gilbert
Browse files

migration: Count new_dirty instead of real_dirty 



real_dirty_pages becomes equal to total ram size after dirty log sync
in ram_init_bitmaps, the reason is that the bitmap of ramblock is
initialized to be all set, so old path counts them as "real dirty" at
beginning.

This causes wrong dirty rate and false positive throttling.

Signed-off-by: default avatarKeqian Zhu <zhukeqian1@huawei.com>
Message-Id: <20200622032037.31112-1-zhukeqian1@huawei.com>
Reviewed-by: default avatarDr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: default avatarDr. David Alan Gilbert <dgilbert@redhat.com>
parent 617a32f5

include/exec/ram_addr.h

+1 −4
Original line number Diff line number Diff line
@@ -442,8 +442,7 @@ 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 length)

{

    ram_addr_t addr;

    unsigned long word = BIT_WORD((start + rb->offset) >> TARGET_PAGE_BITS);
@@ -469,7 +468,6 @@ 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 +500,6 @@ 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++;

migration/ram.c

+5 −3
Original line number Diff line number Diff line
@@ -859,9 +859,11 @@ static inline bool migration_bitmap_clear_dirty(RAMState *rs, 
/* Called with RCU critical section */

static void ramblock_sync_dirty_bitmap(RAMState *rs, RAMBlock *rb)

{

    rs->migration_dirty_pages +=

        cpu_physical_memory_sync_dirty_bitmap(rb, 0, rb->used_length,

                                              &rs->num_dirty_pages_period);

    uint64_t new_dirty_pages =

        cpu_physical_memory_sync_dirty_bitmap(rb, 0, rb->used_length);



    rs->migration_dirty_pages += new_dirty_pages;

    rs->num_dirty_pages_period += new_dirty_pages;

}



/**