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Thu, 17 Dec 2020 07:50:37 +0000 Subject: Re: [PATCH v6 0/4] migration: UFFD write-tracking migration/snapshots To: Peter Xu References: <20201209100811.190316-1-andrey.gruzdev@virtuozzo.com> <3f19b8d2-0b4b-95e3-8a1f-a1cfe791a4e1@virtuozzo.com> <20201211150940.GC6520@xz-x1> <2a1f164c-94ab-0d35-96c0-792524d9ef30@virtuozzo.com> <20201216210226.GB39844@xz-x1> From: Andrey Gruzdev Message-ID: <2f785315-ac85-2335-395f-defa550a6fcf@virtuozzo.com> Date: Thu, 17 Dec 2020 10:50:34 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 In-Reply-To: <20201216210226.GB39844@xz-x1> Content-Type: multipart/alternative; boundary="------------DDCF9BC8C6CBA3DBF72C2F36" Content-Language: en-US X-Originating-IP: [95.165.26.68] X-ClientProxiedBy: AM3PR05CA0148.eurprd05.prod.outlook.com (2603:10a6:207:3::26) To VI1PR0802MB2510.eurprd08.prod.outlook.com (2603:10a6:800:ad::14) MIME-Version: 1.0 X-MS-Exchange-MessageSentRepresentingType: 1 Received: from [192.168.1.64] (95.165.26.68) by AM3PR05CA0148.eurprd05.prod.outlook.com (2603:10a6:207:3::26) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.3654.12 via Frontend Transport; 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envelope-from=andrey.gruzdev@virtuozzo.com; helo=EUR04-VI1-obe.outbound.protection.outlook.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, HTML_MESSAGE=0.001, MSGID_FROM_MTA_HEADER=0.001, NICE_REPLY_A=-0.001, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H2=-0.001, SPF_HELO_PASS=-0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Juan Quintela , Markus Armbruster , qemu-devel@nongnu.org, "Dr . David Alan Gilbert" , Paolo Bonzini , Den Lunev Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" --------------DDCF9BC8C6CBA3DBF72C2F36 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit On 17.12.2020 00:02, Peter Xu wrote: > 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, > Yes, I think it's good to have this script in the same tree. Nice news about 6.0! For v7, I've added a fix for suspended guest since previously we'd finish in assert() on invalid runstate transition when doing initial vm_stop_force_state(RUN_STATE_PAUSED)). Also disabled dirty page logging and log syncing for background snapshots. Thanks, -- Andrey Gruzdev, Principal Engineer Virtuozzo GmbH +7-903-247-6397 virtuzzo.com --------------DDCF9BC8C6CBA3DBF72C2F36 Content-Type: text/html; charset=utf-8 Content-Transfer-Encoding: 7bit
On 17.12.2020 00:02, Peter Xu wrote:
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,


Yes, I think it's good to have this script in the same tree.

Nice news about 6.0! For v7, I've added a fix for suspended guest since previously we'd finish
in assert() on invalid runstate transition when doing initial vm_stop_force_state(RUN_STATE_PAUSED)).
Also disabled dirty page logging and log syncing for background snapshots.

Thanks,

-- 
Andrey Gruzdev, Principal Engineer
Virtuozzo GmbH  +7-903-247-6397
                virtuzzo.com
--------------DDCF9BC8C6CBA3DBF72C2F36--