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Revert "migration: Simplify unqueue_page()"

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This reverts commit cfd66f30fb.

The simplification of unqueue_page() introduced a bug that sometimes
breaks migration on s390x hosts.

The problem is not fully understood yet, but since we are already in
the freeze for QEMU 7.1 and we need something working there, let's
revert this patch for the upcoming release. The optimization can be
redone later again in a proper way if necessary.

Buglink: https://bugzilla.redhat.com/show_bug.cgi?id=2099934
Signed-off-by: Thomas Huth <thuth@redhat.com>
Message-Id: <20220802061949.331576-1-thuth@redhat.com>
Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
This commit is contained in:
Thomas Huth 2022-08-02 08:19:49 +02:00 committed by Dr. David Alan Gilbert
parent df67aa3e61
commit 777f53c759
2 changed files with 28 additions and 12 deletions
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37
migration/ram.c
View File

@ -1612,7 +1612,6 @@ static RAMBlock *unqueue_page(RAMState *rs, ram_addr_t *offset)
{
struct RAMSrcPageRequest *entry;
RAMBlock *block = NULL;
size_t page_size;
if (!postcopy_has_request(rs)) {
return NULL;
@ -1629,13 +1628,10 @@ static RAMBlock *unqueue_page(RAMState *rs, ram_addr_t *offset)
entry = QSIMPLEQ_FIRST(&rs->src_page_requests);
block = entry->rb;
*offset = entry->offset;
page_size = qemu_ram_pagesize(block);
/* Each page request should only be multiple page size of the ramblock */
assert((entry->len % page_size) == 0);
if (entry->len > page_size) {
entry->len -= page_size;
entry->offset += page_size;
if (entry->len > TARGET_PAGE_SIZE) {
entry->len -= TARGET_PAGE_SIZE;
entry->offset += TARGET_PAGE_SIZE;
} else {
memory_region_unref(block->mr);
QSIMPLEQ_REMOVE_HEAD(&rs->src_page_requests, next_req);
@ -1643,9 +1639,6 @@ static RAMBlock *unqueue_page(RAMState *rs, ram_addr_t *offset)
migration_consume_urgent_request();
}
trace_unqueue_page(block->idstr, *offset,
test_bit((*offset >> TARGET_PAGE_BITS), block->bmap));
return block;
}
@ -2069,8 +2062,30 @@ static bool get_queued_page(RAMState *rs, PageSearchStatus *pss)
{
RAMBlock *block;
ram_addr_t offset;
bool dirty;
block = unqueue_page(rs, &offset);
do {
block = unqueue_page(rs, &offset);
/*
* We're sending this page, and since it's postcopy nothing else
* will dirty it, and we must make sure it doesn't get sent again
* even if this queue request was received after the background
* search already sent it.
*/
if (block) {
unsigned long page;
page = offset >> TARGET_PAGE_BITS;
dirty = test_bit(page, block->bmap);
if (!dirty) {
trace_get_queued_page_not_dirty(block->idstr, (uint64_t)offset,
page);
} else {
trace_get_queued_page(block->idstr, (uint64_t)offset, page);
}
}
} while (block && !dirty);
if (block) {
/* See comment above postcopy_preempted_contains() */

3
migration/trace-events
View File

@ -85,6 +85,8 @@ put_qlist_end(const char *field_name, const char *vmsd_name) "%s(%s)"
qemu_file_fclose(void) ""
# ram.c
get_queued_page(const char *block_name, uint64_t tmp_offset, unsigned long page_abs) "%s/0x%" PRIx64 " page_abs=0x%lx"
get_queued_page_not_dirty(const char *block_name, uint64_t tmp_offset, unsigned long page_abs) "%s/0x%" PRIx64 " page_abs=0x%lx"
migration_bitmap_sync_start(void) ""
migration_bitmap_sync_end(uint64_t dirty_pages) "dirty_pages %" PRIu64
migration_bitmap_clear_dirty(char *str, uint64_t start, uint64_t size, unsigned long page) "rb %s start 0x%"PRIx64" size 0x%"PRIx64" page 0x%lx"
@ -110,7 +112,6 @@ ram_save_iterate_big_wait(uint64_t milliconds, int iterations) "big wait: %" PRI
ram_load_complete(int ret, uint64_t seq_iter) "exit_code %d seq iteration %" PRIu64
ram_write_tracking_ramblock_start(const char *block_id, size_t page_size, void *addr, size_t length) "%s: page_size: %zu addr: %p length: %zu"
ram_write_tracking_ramblock_stop(const char *block_id, size_t page_size, void *addr, size_t length) "%s: page_size: %zu addr: %p length: %zu"
unqueue_page(char *block, uint64_t offset, bool dirty) "ramblock '%s' offset 0x%"PRIx64" dirty %d"
postcopy_preempt_triggered(char *str, unsigned long page) "during sending ramblock %s offset 0x%lx"
postcopy_preempt_restored(char *str, unsigned long page) "ramblock %s offset 0x%lx"
postcopy_preempt_hit(char *str, uint64_t offset) "ramblock %s offset 0x%"PRIx64