[Qemu-devel] [PATCH for-1.5] Revert "migration: don't account sleep time for calculating bandwidth"

[Michael Roth]

This reverts commit 7161082c8d8cf167c508976887a0a63f4db92b51.

Reverting this patch fixes a divide-by-zero error in qemu that can be
fairly reliably triggered by doing block migration. In this case, the
configuration/error was:

source: temp/x86_64-softmmu/qemu-system-x86_64 -enable-kvm -L temp-bios
-M pc-i440fx-1.4 -m 512M -kernel boot/vmlinuz-x86_64 -initrd
boot/test-initramfs-x86_64.img.gz -vga std -append seed=1234 -drive
file=disk1.img,if=virtio -drive file=disk2.img,if=virtio -device
virtio-net-pci,netdev=net0 -netdev user,id=net0 -monitor
unix:/tmp/vm-hmp.sock,server,nowait -qmp
unix:/tmp/vm-qmp.sock,server,nowait -vnc :100

16837 Floating point exception(core dumped)

target: temp/x86_64-softmmu/qemu-system-x86_64 -enable-kvm -L temp-bios
-M pc-i440fx-1.4 -m 512M -kernel boot/vmlinuz-x86_64 -initrd
boot/test-initramfs-x86_64.img.gz -vga std -append seed=1234 -drive
file=target_disk1.img,if=virtio -drive file=target_disk2.img,if=virtio
-device virtio-net-pci,netdev=net0 -netdev user,id=net0 -incoming
unix:/tmp/migrate.sock -monitor
unix:/tmp/vm-hmp-incoming.sock,server,nowait -qmp
unix:/tmp/vm-qmp-incoming.sock,server,nowait -vnc :101

Receiving block device images
20 %
21 %
load of migration failed

This revert potentially re-introduces a bug that was present in 1.4,
but fixes a prevalent issue with block migration so we should revert
it for now and take an updated patch later.

Conflicts:

        migration.c

* fixed up to remove logic introduced in 7161082c while leaving
  changes in HEAD intact

Signed-off-by: Michael Roth <address@hidden>
---
 migration.c |    5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/migration.c b/migration.c
index 3eb0fad..bfbc345 100644
--- a/migration.c
+++ b/migration.c
@@ -498,7 +498,6 @@ static void *migration_thread(void *opaque)
 {
     MigrationState *s = opaque;
     int64_t initial_time = qemu_get_clock_ms(rt_clock);
-    int64_t sleep_time = 0;
     int64_t initial_bytes = 0;
     int64_t max_size = 0;
     int64_t start_time = initial_time;
@@ -541,7 +540,7 @@ static void *migration_thread(void *opaque)
         current_time = qemu_get_clock_ms(rt_clock);
         if (current_time >= initial_time + BUFFER_DELAY) {
             uint64_t transferred_bytes = qemu_ftell(s->file) - initial_bytes;
-            uint64_t time_spent = current_time - initial_time - sleep_time;
+            uint64_t time_spent = current_time - initial_time;
             double bandwidth = transferred_bytes / time_spent;
             max_size = bandwidth * migrate_max_downtime() / 1000000;
 
@@ -555,14 +554,12 @@ static void *migration_thread(void *opaque)
             }
 
             qemu_file_reset_rate_limit(s->file);
-            sleep_time = 0;
             initial_time = current_time;
             initial_bytes = qemu_ftell(s->file);
         }
         if (qemu_file_rate_limit(s->file)) {
             /* usleep expects microseconds */
             g_usleep((initial_time + BUFFER_DELAY - current_time)*1000);
-            sleep_time += qemu_get_clock_ms(rt_clock) - current_time;
         }
     }
 
-- 
1.7.9.5