exec: change ramlist from MRU order to a 1-item cache

Most of the time, only 2 items will be active (from/to for a string operation,
or code/data).  But TCG guests likely won't have gigabytes of memory, so
this actually goes down to 1 item.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
exec: change RAM list to a TAILQ

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
exec: sort the memory from biggest to smallest

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
add a version number to ram_list

This will be used to detect if last_block might have become invalid
across different calls to ram_save_live.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Umesh Deshpande <udeshpan@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>

Reviewed-by: Orit Wasserman <owasserm@redhat.com>
protect the ramlist with a separate mutex

Add the new mutex that protects shared state between ram_save_live
and the iothread.  If the iothread mutex has to be taken together
with the ramlist mutex, the iothread shall always be _outside_.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Umesh Deshpande <udeshpan@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>

Reviewed-by: Orit Wasserman <owasserm@redhat.com>
buffered_file: Move from using a timer to use a thread

We still protect everything except the wait with the iothread lock.
But we moved from a timer to a thread.  Steps one by one.

We also need to detect when we have finished with a variable "complete".

Signed-off-by: Juan Quintela <quintela@redhat.com>
migration: make qemu_fopen_ops_buffered() return void

We want the file assignment to happen before the thread is created to
avoid locking, so we just do it before creating the thread.

Signed-off-by: Juan Quintela <quintela@redhat.com>

Reviewed-by: Orit Wasserman <owasserm@redhat.com>
migration: move migration thread init code to migrate_fd_put_ready

This way everything related with migration is run on the migration
thread and no locking is needed.

Signed-off-by: Juan Quintela <quintela@redhat.com>
migration: make writes blocking

Move all the writes to the migration_thread, and make writings
blocking.  Notice that are still using the iothread for everything
that we do.

Signed-off-by: Juan Quintela <quintela@redhat.com>
migration: remove unfreeze logic

Now that we have a thread, and blocking writes, we don't need it.

Signed-off-by: Juan Quintela <quintela@redhat.com>

Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
migration: just lock migrate_fd_put_ready

Signed-off-by: Juan Quintela <quintela@redhat.com>
buffered_file: Unfold the trick to restart generating migration data

This was needed before due to the way that the callbacks worked.

Signed-off-by: Juan Quintela <quintela@redhat.com>

Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
buffered_file: don't flush on put buffer

We call buffered_put_buffer with iothread held, and buffered_flush() does
synchronous writes.  We only want to do the synchronous writes outside.

Signed-off-by: Juan Quintela <quintela@redhat.com>

Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
buffered_file: unfold buffered_append in buffered_put_buffer

It was the only user, and now buffered_put_buffer just do the append

Signed-off-by: Juan Quintela <quintela@redhat.com>

Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
savevm: New save live migration method: pending

Code just now does (simplified for clarity)

    if (qemu_savevm_state_iterate(s->file) == 1) {
       vm_stop_force_state(RUN_STATE_FINISH_MIGRATE);
       qemu_savevm_state_complete(s->file);
    }

Problem here is that qemu_savevm_state_iterate() returns 1 when it
knows that remaining memory to sent takes less than max downtime.

But this means that we could end spending 2x max_downtime, one
downtime in qemu_savevm_iterate, and the other in
qemu_savevm_state_complete.

Changed code to:

    pending_size = qemu_savevm_state_pending(s->file, max_size);
    DPRINTF("pending size %lu max %lu\n", pending_size, max_size);
    if (pending_size >= max_size) {
        ret = qemu_savevm_state_iterate(s->file);
     } else {
        vm_stop_force_state(RUN_STATE_FINISH_MIGRATE);
        qemu_savevm_state_complete(s->file);
     }

So what we do is: at current network speed, we calculate the maximum
number of bytes we can sent: max_size.

Then we ask every save_live section how much they have pending.  If
they are less than max_size, we move to complete phase, otherwise we
do an iterate one.

This makes things much simpler, because now individual sections don't
have to caluclate the bandwidth (it was implossible to do right from
there).

Signed-off-by: Juan Quintela <quintela@redhat.com>

Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
migration: move buffered_file.c code into migration.c

This only moves the code (also from buffered_file.h to migration.h).
Fix whitespace until checkpatch is happy.

Signed-off-by: Juan Quintela <quintela@redhat.com>
migration: add XFER_LIMIT_RATIO

The "magic" divisions by 10 are there because of the value of BUFFER_DELAY.
Introduce a constant to explain them better.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
migration: move migration_fd_put_ready()

Put it near its use and un-export it.

Signed-off-by: Juan Quintela <quintela@redhat.com>
migration: Inline qemu_fopen_ops_buffered into migrate_fd_connect

Signed-off-by: Juan Quintela <quintela@redhat.com>
migration: move migration notifier

At this point, it is waranteed that state is ACTIVE.  Old position
didn't assured hat.

Signed-off-by: Juan Quintela <quintela@redhat.com>