On Tue, Dec 15, 2020 at 10:53:13PM +0300, Andrey Gruzdev wrote: > First are series of runs without scan-rate-limiting.patch. > Windows 10: > > msecs : count distribution > 0 -> 1 : 131913 |****************************************| > 2 -> 3 : 106 | | > 4 -> 7 : 362 | | > 8 -> 15 : 619 | | > 16 -> 31 : 28 | | > 32 -> 63 : 1 | | > 64 -> 127 : 2 | | > > > msecs : count distribution > 0 -> 1 : 199273 |****************************************| > 2 -> 3 : 190 | | > 4 -> 7 : 425 | | > 8 -> 15 : 927 | | > 16 -> 31 : 69 | | > 32 -> 63 : 3 | | > 64 -> 127 : 16 | | > 128 -> 255 : 2 | | > > Ubuntu 20.04: > > msecs : count distribution > 0 -> 1 : 104954 |****************************************| > 2 -> 3 : 9 | | > > msecs : count distribution > 0 -> 1 : 147159 |****************************************| > 2 -> 3 : 13 | | > 4 -> 7 : 0 | | > 8 -> 15 : 0 | | > 16 -> 31 : 0 | | > 32 -> 63 : 0 | | > 64 -> 127 : 1 | | > > > Here are runs with scan-rate-limiting.patch. > Windows 10: > > msecs : count distribution > 0 -> 1 : 234492 |****************************************| > 2 -> 3 : 66 | | > 4 -> 7 : 219 | | > 8 -> 15 : 109 | | > 16 -> 31 : 0 | | > 32 -> 63 : 0 | | > 64 -> 127 : 1 | | > > msecs : count distribution > 0 -> 1 : 183171 |****************************************| > 2 -> 3 : 109 | | > 4 -> 7 : 281 | | > 8 -> 15 : 444 | | > 16 -> 31 : 3 | | > 32 -> 63 : 1 | | > > Ubuntu 20.04: > > msecs : count distribution > 0 -> 1 : 92224 |****************************************| > 2 -> 3 : 9 | | > 4 -> 7 : 0 | | > 8 -> 15 : 0 | | > 16 -> 31 : 1 | | > 32 -> 63 : 0 | | > 64 -> 127 : 1 | | > > msecs : count distribution > 0 -> 1 : 97021 |****************************************| > 2 -> 3 : 7 | | > 4 -> 7 : 0 | | > 8 -> 15 : 0 | | > 16 -> 31 : 0 | | > 32 -> 63 : 0 | | > 64 -> 127 : 0 | | > 128 -> 255 : 1 | | > > So, initial variant of rate-limiting makes some positive effect, but not very > noticible. Interesting is the case of Windows guest, why the difference is so > large, > compared to Linux. The reason (theoretically) might be some of virtio or QXL > drivers, > hard to say. At least Windows VM has been configured with a set of Hyper-V > enlightments, there's nothing to improve in domain config. > > For Linux guests latencies are good enough without any additional efforts.
Interesting... > > Also, I've missed some code to deal with snapshotting of suspended guest, so > I'll made > v7 series with the fix and also try to add more effective solution to reduce > millisecond-grade > latencies. > > And yes, I've used bpftrace-like tool - BCC from iovisor with python > frontend. Seems a bit more > friendly then bpftrace. Do you think it's a good idea to also include your measurement script when posting v7? It could be a well fit for scripts/, I think. Seems 6.0 dev window is open; hopefully Dave or Juan would have time to look at this series soon. Thanks, -- Peter Xu
