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,