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Re: [Qemu-devel] bitmap
From: |
Stefan Hajnoczi |
Subject: |
Re: [Qemu-devel] bitmap |
Date: |
Mon, 22 May 2017 16:45:01 +0100 |
User-agent: |
Mutt/1.8.0 (2017-02-23) |
On Mon, May 22, 2017 at 06:00:12PM +0430, ali saeedi wrote:
> does this code 'atomic_rcu_read(&migration_bitmap_rcu)->bmap' return bitmap
> of dirty blocks or bitmap of pages?
This code changed recently. Please refer to qemu.git/master when asking
questions on qemu-devel.
I think you're asking about what is now RAMBlock->bmap. This bitmap
describes pages (each page is TARGET_PAGE_SIZE bytes).
This comment looks outdated, I don't think it returns a byte offset:
/**
* migration_bitmap_find_dirty: find the next dirty page from start
*
* Called with rcu_read_lock() to protect migration_bitmap
*
* Returns the byte offset within memory region of the start of a dirty page
*
* @rs: current RAM state
* @rb: RAMBlock where to search for dirty pages
* @start: page where we start the search
*/
static inline
unsigned long migration_bitmap_find_dirty(RAMState *rs, RAMBlock *rb,
unsigned long start)
Evidence:
static bool find_dirty_block(RAMState *rs, PageSearchStatus *pss, bool *again)
{
pss->page = migration_bitmap_find_dirty(rs, pss->block, pss->page);
...
if ((pss->page << TARGET_PAGE_BITS) >= pss->block->used_length) {
Stefan
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