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Last change
on this file was 107390, checked in by vboxsync, 8 weeks ago |
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Docs: bugref:10705. bugref: 10829. The docs build has been modified to split generated refentry dita files and the user manual files and the following commits from doc's team git repo has been applied:
0946136c74dda0483704db891345cb39548b4e28 Started consolidating known issues and troubleshooting information
845b847e6a8e778b38a57867e25ee5e086a73800 Added individual topics for list of known issues, integrated into Troubleshooting section.
bb574836aac775889bd61e4a72f489617fcb7d18 Removed EFI firmware from experimental features for 7.2
6d2e68b244869991e713d170ecd239739d99ba56 Moved known issues into Known Issues section
e2630c896561587718b5c3197c384a38d07014d5 Merge branch 'VBP-1461_experimental-features' into 'main'
0512e2cce51f49ccdc56f3381a2a0c924f2bd278 Feedback on known issues
a77d6c980f6ff5cad9d32b2fb9290990093a03fa Restructured host and guest OS topics
988af5cc9628f5de0806531bc98686f691a911fd Updates with feedbback from Jacob
982a61c9f25b22b745ec483e763e3d88efe59c40 Included feedback from Jacob
93181c8c6cc2d9a26bcccb1145cb0423c0d9f4c9 Updated known issues with feedback from Klaus
8bc369561c383f09b409fe5e44f507440b3735fb Created Legacy Guest OS section
d7932f55accdab7a03666302d58b8c941cd48be2 Moved known issues to more appropriate places for the info
2a4aa094ba8a7ac6894d2a777316eabf41746580 Further moving of known issues
baeabd5308c5519a4dc26b4197be9b00e419a85a Updated links to cli_topics
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| 1 | <?xml version='1.0' encoding='UTF-8'?>
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| 2 | <!DOCTYPE topic PUBLIC "-//OASIS//DTD DITA Topic//EN" "topic.dtd">
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| 3 | <topic xml:lang="en-us" id="ts_host-freq-scaling">
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| 4 | <title>Frequency Scaling Effect on CPU Usage</title>
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| 5 |
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| 6 | <body>
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| 7 | <p>
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| 8 | On some hardware platforms and operating systems, CPU frequency
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| 9 | scaling may cause CPU usage reporting to be highly misleading.
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| 10 | This happens in situations when the host CPU load is significant
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| 11 | but not heavy, such as between 15% to 30% of the maximum.
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| 12 | </p>
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| 13 | <p>
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| 14 | Most operating systems determine CPU usage in terms of time
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| 15 | spent, measuring for example how many nanoseconds the systems or
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| 16 | a process was active within one second. However, in order to
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| 17 | save energy, systems can significantly scale down CPU speed when
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| 18 | the system is not fully loaded. When the CPU is running at for
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| 19 | example one half of its maximum speed, the same number of
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| 20 | instructions will take roughly twice as long to execute compared
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| 21 | to running at full speed.
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| 22 | </p>
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| 23 | <p>
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| 24 | Depending on the specific hardware and host OS, this effect can
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| 25 | very significantly skew the CPU usage reported by the OS. The
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| 26 | reported CPU usage can be several times higher than what it
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| 27 | would have been had the CPU been running at full speed. The
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| 28 | effect can be observed both on the host OS and in a guest OS.
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| 29 | </p>
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| 30 | </body>
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| 31 |
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| 32 | </topic>
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