misc: align structs for modern 64-bit platforms #1379
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Affected structs: - _UDisksLinuxDriveAta - SynthUeventData -_UDisksBaseJobPrivate
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Jenkins, ok to test. |
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Well I understand your point of optimizing cachelines, though its real impact is questionable in a project that spends much more CPU cycles with GObject machinery, marshalling/demarshalling data types and translating structures for D-Bus objects. Especially in the context of data structures that are not so often used. FYI, beware of certain GObject requirements for subclassing (that are not an issue in this PR), such as embedding whole structs of parent classes (as a first struct member). |
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Updated to master branch. |
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@tbzatek,
This PR will decrease costs copying, moving, and creating object-structures only for common 64bit processors due to the 8-byte data alignment.
Smaller size structure or class, higher chance putting into CPU cache. Most processors are already 64 bit, so the change won't make it any worse.
Info about technique:
https://hpc.rz.rptu.de/Tutorials/AVX/alignment.shtml
https://wr.informatik.uni-hamburg.de/_media/teaching/wintersemester_2013_2014/epc-14-haase-svenhendrik-alignmentinc-presentation.pdf
https://en.wikipedia.org/wiki/Data_structure_alignment
https://stackoverflow.com/a/20882083
https://zijishi.xyz/post/optimization-technique/learning-to-use-data-alignment/
Affected structs: