Commit 4508bd9e authored by Juan Quintela's avatar Juan Quintela
Browse files

Exit loop if we have been there too long 



Checking each 64 pages is a random magic number as good as any other.
We don't want to test too many times, but on the other hand,
qemu_get_clock_ns() is not so expensive either.  We want to be sure
that we spent less than 50ms (half of buffered_file timer), if we
spent more than 100ms, all the accounting got wrong.

Signed-off-by: default avatarJuan Quintela <quintela@redhat.com>
parent 5b3c9638

arch_init.c

+18 −0
Original line number Diff line number Diff line
@@ -309,12 +309,15 @@ static void migration_end(void) 
    memory_global_dirty_log_stop();

}



#define MAX_WAIT 50 /* ms, half buffered_file limit */



int ram_save_live(QEMUFile *f, int stage, void *opaque)

{

    ram_addr_t addr;

    uint64_t bytes_transferred_last;

    double bwidth = 0;

    int ret;

    int i;



    if (stage < 0) {

        migration_end();
@@ -354,6 +357,7 @@ int ram_save_live(QEMUFile *f, int stage, void *opaque) 
    bytes_transferred_last = bytes_transferred;

    bwidth = qemu_get_clock_ns(rt_clock);



    i = 0;

    while ((ret = qemu_file_rate_limit(f)) == 0) {

        int bytes_sent;
@@ -362,6 +366,20 @@ int ram_save_live(QEMUFile *f, int stage, void *opaque) 
        if (bytes_sent == 0) { /* no more blocks */

            break;

        }

        /* we want to check in the 1st loop, just in case it was the 1st time

           and we had to sync the dirty bitmap.

           qemu_get_clock_ns() is a bit expensive, so we only check each some

           iterations

        */

        if ((i & 63) == 0) {

            uint64_t t1 = (qemu_get_clock_ns(rt_clock) - bwidth) / 1000000;

            if (t1 > MAX_WAIT) {

                DPRINTF("big wait: " PRIu64 " milliseconds, %d iterations\n",

                        t1, i);

                break;

            }

        }

        i++;

    }



    if (ret < 0) {