Changes

1,149 bytes added ,  13:31, 25 August 2020
The article has been updated to include the performance impact of the changes made as part of GSoC 2020.
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To explicitly use only the file size check all the time, the following command-line option can be used: <code>--file-validation filesize</code> (This is the fastest and least intensive check).
 
To explicitly use only the file size check all the time, the following command-line option can be used: <code>--file-validation filesize</code> (This is the fastest and least intensive check).
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== Performance impact ==
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The values shown below are the average times it took to finish the ZDTM tests over multiple runs, and are only to indicate the impact each method has in general.
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Each test has 3 files (Of sizes: 0.09 MB, 2 MB and 0.17 MB approximately) and each test is run 3 times (In Host, Namespace and User Namespace). For each file the checksum/build-ID is obtained twice (During dump and restore) therefore the function to find checksum/build-ID is called 18 times overall per test.
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For reference, these tests were run on tmpfs (To remove any disk latency) and on an undervolted i5 4800H.
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{| class="wikitable"
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|+zdtm/transition/shmem:
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|-
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|File Size
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|3.782s
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|-
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|Build-ID
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|4.153s (~9% increase)
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|-
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|Checksum (First 1024 bytes)
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|4.465s (~18% increase)
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|-
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|Checksum (Entire File)
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|4.722s (~24% increase)
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|-
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|Checksum (Every 1024th byte)
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|4.498s (~19% increase)
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|}
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{| class="wikitable"
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|+zdtm/static/maps04:
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|-
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|File Size
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|35.317s
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|-
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|Build-ID
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|35.720s (~1% increase)
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|-
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|Checksum (First 1024 bytes)
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|35.919s (~2% increase)
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|-
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|Checksum (Entire File)
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|36.679s (~4% increase)
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|-
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|Checksum (Every 1024th byte)
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|36.476s (~3% increase)
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|}
    
== Scope for improvement and future work ==
 
== Scope for improvement and future work ==