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migration: Use non-atomic ops for clear log bitmap

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Since we already have bitmap_mutex to protect either the dirty bitmap or
the clear log bitmap, we don't need atomic operations to set/clear/test on
the clear log bitmap.  Switching all ops from atomic to non-atomic
versions, meanwhile touch up the comments to show which lock is in charge.

Introduced non-atomic version of bitmap_test_and_clear_atomic(), mostly the
same as the atomic version but simplified a few places, e.g. dropped the
"old_bits" variable, and also the explicit memory barriers.

Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
This commit is contained in:
Peter Xu 2022-10-04 14:24:29 -04:00 • committed by Juan Quintela
parent afed4273b5
commit cedb70eafb
4 changed files with 55 additions and 5 deletions
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11
include/exec/ram_addr.h
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@ -42,7 +42,8 @@ static inline long clear_bmap_size(uint64_t pages, uint8_t shift)
}
/**
* clear_bmap_set: set clear bitmap for the page range
* clear_bmap_set: set clear bitmap for the page range. Must be with
* bitmap_mutex held.
*
* @rb: the ramblock to operate on
* @start: the start page number
@ -55,12 +56,12 @@ static inline void clear_bmap_set(RAMBlock *rb, uint64_t start,
{
uint8_t shift = rb->clear_bmap_shift;
bitmap_set_atomic(rb->clear_bmap, start >> shift,
clear_bmap_size(npages, shift));
bitmap_set(rb->clear_bmap, start >> shift, clear_bmap_size(npages, shift));
}
/**
* clear_bmap_test_and_clear: test clear bitmap for the page, clear if set
* clear_bmap_test_and_clear: test clear bitmap for the page, clear if set.
* Must be with bitmap_mutex held.
*
* @rb: the ramblock to operate on
* @page: the page number to check
@ -71,7 +72,7 @@ static inline bool clear_bmap_test_and_clear(RAMBlock *rb, uint64_t page)
{
uint8_t shift = rb->clear_bmap_shift;
return bitmap_test_and_clear_atomic(rb->clear_bmap, page >> shift, 1);
return bitmap_test_and_clear(rb->clear_bmap, page >> shift, 1);
}
static inline bool offset_in_ramblock(RAMBlock *b, ram_addr_t offset)