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migration: rename max_size to threshold_size

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In migration codes (especially in migration_thread()), max_size is used
in many place for the threshold value that we will start to do the final
flush and jump to the next stage to dump the whole rest things to
destination. However its name is confusing to first readers. Let's
rename it to "threshold_size" when proper and add a comment for it. No
functional change is made.

CC: Juan Quintela <quintela@redhat.com>
CC: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
Signed-off-by: Peter Xu <peterx@redhat.com>
Reviewed-by: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
This commit is contained in:
Peter Xu 2017-04-01 16:18:43 +08:00 • committed by Juan Quintela
parent 343001f68d
commit faec066ab8
3 changed files with 17 additions and 11 deletions
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21
migration/migration.c
View file

@ -1910,7 +1910,12 @@ static void *migration_thread(void *opaque)
int64_t initial_time = qemu_clock_get_ms(QEMU_CLOCK_REALTIME);
int64_t setup_start = qemu_clock_get_ms(QEMU_CLOCK_HOST);
int64_t initial_bytes = 0;
int64_t max_size = 0;
/*
* The final stage happens when the remaining data is smaller than
* this threshold; it's calculated from the requested downtime and
* measured bandwidth
*/
int64_t threshold_size = 0;
int64_t start_time = initial_time;
int64_t end_time;
bool old_vm_running = false;
@ -1954,17 +1959,17 @@ static void *migration_thread(void *opaque)
if (!qemu_file_rate_limit(s->to_dst_file)) {
uint64_t pend_post, pend_nonpost;
qemu_savevm_state_pending(s->to_dst_file, max_size, &pend_nonpost,
&pend_post);
qemu_savevm_state_pending(s->to_dst_file, threshold_size,
&pend_nonpost, &pend_post);
pending_size = pend_nonpost + pend_post;
trace_migrate_pending(pending_size, max_size,
trace_migrate_pending(pending_size, threshold_size,
pend_post, pend_nonpost);
if (pending_size && pending_size >= max_size) {
if (pending_size && pending_size >= threshold_size) {
/* Still a significant amount to transfer */
if (migrate_postcopy_ram() &&
s->state != MIGRATION_STATUS_POSTCOPY_ACTIVE &&
pend_nonpost <= max_size &&
pend_nonpost <= threshold_size &&
atomic_read(&s->start_postcopy)) {
if (!postcopy_start(s, &old_vm_running)) {
@ -1996,13 +2001,13 @@ static void *migration_thread(void *opaque)
initial_bytes;
uint64_t time_spent = current_time - initial_time;
double bandwidth = (double)transferred_bytes / time_spent;
max_size = bandwidth * s->parameters.downtime_limit;
threshold_size = bandwidth * s->parameters.downtime_limit;
s->mbps = (((double) transferred_bytes * 8.0) /
((double) time_spent / 1000.0)) / 1000.0 / 1000.0;
trace_migrate_transferred(transferred_bytes, time_spent,
bandwidth, max_size);
bandwidth, threshold_size);
/* if we haven't sent anything, we don't want to recalculate
10000 is a small enough number for our purposes */
if (ram_dirty_pages_rate() && transferred_bytes > 10000) {