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Re: [PATCH v6 0/4] migration: UFFD write-tracking migration/snapshots
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From: |
Peter Xu |
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Subject: |
Re: [PATCH v6 0/4] migration: UFFD write-tracking migration/snapshots |
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Date: |
Wed, 16 Dec 2020 16:02:26 -0500 |
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
- [PATCH v6 0/4] migration: UFFD write-tracking migration/snapshots, Andrey Gruzdev, 2020/12/09
- [PATCH v6 1/4] migration: introduce 'background-snapshot' migration capability, Andrey Gruzdev, 2020/12/09
- [PATCH v6 2/4] migration: introduce UFFD-WP low-level interface helpers, Andrey Gruzdev, 2020/12/09
- [PATCH v6 3/4] migration: support UFFD write fault processing in ram_save_iterate(), Andrey Gruzdev, 2020/12/09
- [PATCH v6 4/4] migration: implementation of background snapshot thread, Andrey Gruzdev, 2020/12/09
- Re: [PATCH v6 0/4] migration: UFFD write-tracking migration/snapshots, Andrey Gruzdev, 2020/12/11
- Re: [PATCH v6 0/4] migration: UFFD write-tracking migration/snapshots, Andrey Gruzdev, 2020/12/15