Author vstinner
Recipients benjamin.peterson, fweimer, gregory.p.smith, methane, nascheme, pitrou, skrah, tgrigg, twouters, vstinner
Date 2019-05-22.00:09:17
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Message-id <1558483757.34.0.114918637339.issue27987@roundup.psfhosted.org>
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> It seems to me that we don't need to have the PyObject structure containing a Python float to be 16-byte aligned.  If so, could we introduce a new obmalloc API that returns memory with 8-byte alignment, for use by objects that know they don't require 16-byte alignment?  floatobject.c could use this API to avoid the 33% overhead.

PyMem_Malloc / PyObject_Malloc only have one parameter: "size". It knows nothing about the allocated structure.

bpo-18835 discussed the idea of adding a new API which accept an alignment parameter. The issue was closed because of the lack of concrete usage.

In the clang crash bpo-36618 (which decided us to fix this issue), C alignof() function was discussed:
https://bugs.python.org/issue36618#msg340279

Copy of serge-sans-paille's comment:

"@vstinner: once you have a portable version of alignof, you can deciding to *not* use the pool allocator if the required alignment is greater than 8B, or you could modify the pool allocator to take alignment information as an extra parameter?"
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Date User Action Args
2019-05-22 00:09:17vstinnersetrecipients: + vstinner, twouters, nascheme, gregory.p.smith, pitrou, benjamin.peterson, methane, skrah, fweimer, tgrigg
2019-05-22 00:09:17vstinnersetmessageid: <1558483757.34.0.114918637339.issue27987@roundup.psfhosted.org>
2019-05-22 00:09:17vstinnerlinkissue27987 messages
2019-05-22 00:09:17vstinnercreate