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e02f56e3de
The migration test cases that actually exercise live migration want to ensure there is a minimum of two iterations of pre-copy, in order to exercise the dirty tracking code. Historically we've queried the migration status, looking for the 'dirty-sync-count' value to increment to track iterations. This was not entirely reliable because often all the data would get transferred quickly enough that the migration would finish before we wanted it to. So we massively dropped the bandwidth and max downtime to guarantee non-convergance. This had the unfortunate side effect that every migration took at least 30 seconds to run (100 MB of dirty pages / 3 MB/sec). This optimization takes a different approach to ensuring that a mimimum of two iterations. Rather than waiting for dirty-sync-count to increment, directly look for an indication that the source VM has dirtied RAM that has already been transferred. On the source VM a magic marker is written just after the 3 MB offset. The destination VM is now montiored to detect when the magic marker is transferred. This gives a guarantee that the first 3 MB of memory have been transferred. Now the source VM memory is monitored at exactly the 3MB offset until we observe a flip in its value. This gives us a guaranteed that the guest workload has dirtied a byte that has already been transferred. Since we're looking at a place that is only 3 MB from the start of memory, with the 3 MB/sec bandwidth, this test should complete in 1 second, instead of 30 seconds. Once we've proved there is some dirty memory, migration can be set back to full speed for the remainder of the 1st iteration, and the entire of the second iteration at which point migration should be complete. On a test machine this further reduces the migration test time from 8 minutes to 1 minute 40. Signed-off-by: Daniel P. Berrangé <berrange@redhat.com> Message-Id: <20230601161347.1803440-11-berrange@redhat.com> Signed-off-by: Thomas Huth <thuth@redhat.com> |
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| .. | ||
| avocado | ||
| bench | ||
| data | ||
| decode | ||
| docker | ||
| fp | ||
| guest-debug | ||
| image-fuzzer | ||
| include | ||
| keys | ||
| lcitool | ||
| migration | ||
| multiboot | ||
| perf/block/qcow2 | ||
| plugin | ||
| qapi-schema | ||
| qemu-iotests | ||
| qtest | ||
| rocker | ||
| tcg | ||
| tsan | ||
| uefi-test-tools | ||
| unit | ||
| vm | ||
| vmstate-static-checker-data | ||
| dbus-vmstate-daemon.sh | ||
| Makefile.include | ||
| meson.build | ||
| requirements.txt | ||
| test-qht-par.c | ||
| vhost-user-bridge.c | ||