12.03.2018 18:30, Dr. David Alan Gilbert wrote:
* Vladimir Sementsov-Ogievskiy (vsement...@virtuozzo.com) wrote:
There would be savevm states (dirty-bitmap) which can migrate only in
postcopy stage. The corresponding pending is introduced here.
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsement...@virtuozzo.com>
---
[...]
static MigIterateState migration_iteration_run(MigrationState *s)
{
- uint64_t pending_size, pend_post, pend_nonpost;
+ uint64_t pending_size, pend_pre, pend_compat, pend_post;
bool in_postcopy = s->state == MIGRATION_STATUS_POSTCOPY_ACTIVE;
- qemu_savevm_state_pending(s->to_dst_file, s->threshold_size,
- &pend_nonpost, &pend_post);
- pending_size = pend_nonpost + pend_post;
+ qemu_savevm_state_pending(s->to_dst_file, s->threshold_size, &pend_pre,
+ &pend_compat, &pend_post);
+ pending_size = pend_pre + pend_compat + pend_post;
trace_migrate_pending(pending_size, s->threshold_size,
- pend_post, pend_nonpost);
+ pend_pre, pend_compat, pend_post);
if (pending_size && pending_size >= s->threshold_size) {
/* Still a significant amount to transfer */
if (migrate_postcopy() && !in_postcopy &&
- pend_nonpost <= s->threshold_size &&
- atomic_read(&s->start_postcopy)) {
+ pend_pre <= s->threshold_size &&
+ (atomic_read(&s->start_postcopy) ||
+ (pend_pre + pend_compat <= s->threshold_size)))
This change does something different from the description;
it causes a postcopy_start even if the user never ran the postcopy-start
command; so sorry, we can't do that; because postcopy for RAM is
something that users can enable but only switch into when they've given
up on it completing normally.
However, I guess that leaves you with a problem; which is what happens
to the system when you've run out of pend_pre+pend_compat but can't
complete because pend_post is non-0; so I don't know the answer to that.
Hmm. Here, we go to postcopy only if "pend_pre + pend_compat <=
s->threshold_size". Pre-patch, in this case we will go to
migration_completion(). So, precopy stage is finishing anyway. So, we
want in this case to finish ram migration like it was finished by
migration_completion(), and then, run postcopy, which will handle only
dirty bitmaps, yes?
Hmm2. Looked through migration_completion(), I don't understand, how it
finishes ram migration without postcopy. It calls
qemu_savevm_state_complete_precopy(), which skips states with
has_postcopy=true, which is ram...
--
Best regards,
Vladimir
