On 02/03/2010 04:47 PM, Michael Goldish wrote:
----- "Uri Lublin"<uril@xxxxxxxxxx> wrote:
Signed-off-by: Uri Lublin<uril@xxxxxxxxxx>
---
client/tests/kvm/tests/timedrift.py | 2 +-
1 files changed, 1 insertions(+), 1 deletions(-)
diff --git a/client/tests/kvm/tests/timedrift.py
b/client/tests/kvm/tests/timedrift.py
index b3e8770..06f6a70 100644
--- a/client/tests/kvm/tests/timedrift.py
+++ b/client/tests/kvm/tests/timedrift.py
@@ -160,7 +160,7 @@ def run_timedrift(test, params, env):
# Report results
host_delta_total = ht2 - ht0
guest_delta_total = gt2 - gt0
- drift_total = 100.0 * (host_delta_total - guest_delta_total) /
host_delta
+ drift_total = 100.0 * (host_delta_total - guest_delta_total) /
host_delta_total
This isn't a typo.
delta_total is the load duration (e.g. 1 min of video decoding) +
rest duration (e.g. 20 secs of idleness).
I think the load drift and the total drift should be divided by the
same delta, in order to determine the amount of drift corrected during
idleness. If you divide the total drift by delta_total (instead of
delta) you give a false impression that more drift was corrected than
really was.
I'm not sure I'm making my point clearly so here's an example:
Let's assume:
- The load duration is 30s;
- the idle duration is 30s;
- the drift was 10s;
- the drift was not corrected at all during idleness -- so after the
idle period the drift remained 10s.
Then:
- The "load drift" is 33.3% (10/30);
- if you divide by delta, the "total drift" is still 33.3% (10/30);
- if you divide by delta_total, the "total drift" is 16.6% (10/60).
So dividing by delta_total gives the impression that some drift was
corrected, when in fact none was.
O.K. That makes sense. Thanks for the explanation.
In your example, the "total drift" is 33% of "the load duration", which is a bit
confusing.
--
To unsubscribe from this list: send the line "unsubscribe kvm" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
