Message 292257 - Python tracker

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Author	vstinner
Recipients	jtaylor, mapreri, methane, vstinner
Date	2017-04-25.09:05:45
SpamBayes Score	-1.0
Marked as misclassified	Yes
Message-id	<1493111145.88.0.621571946728.issue30150@psf.upfronthosting.co.za>
In-reply-to

Content
> On for example x32 malloc returns 16 byte aligned memory but size_t is 4 bytes. x32 is a strange platform :-( Does numpy support it? I'm not sure that Python works on such platform. I suggest to hardcode 16 or 32 bytes in _PyMem_DebugRawAlloc instead of relying on sizeof(size_t). pymalloc aligns memory allocations to 8 bytes if I recall correctly. > How it cause problem? numpy uses SIMD instructions which require strict memory alignement. Note: There was also an issue #18835 to "Add aligned memory variants to the suite of PyMem functions/macros", but it was rejected.

> On for example x32 malloc returns 16 byte aligned memory but size_t is 4 bytes.

x32 is a strange platform :-( Does numpy support it? I'm not sure that Python works on such platform.

I suggest to hardcode 16 or 32 bytes in _PyMem_DebugRawAlloc instead of relying on sizeof(size_t). pymalloc aligns memory allocations to 8 bytes if I recall correctly.


> How it cause problem?

numpy uses SIMD instructions which require strict memory alignement.

Note: There was also an issue #18835 to "Add aligned memory variants to the suite of PyMem functions/macros", but it was rejected.

History
Date	User	Action	Args
2017-04-25 09:05:45	vstinner	set	recipients: + vstinner, methane, jtaylor, mapreri
2017-04-25 09:05:45	vstinner	set	messageid: <1493111145.88.0.621571946728.issue30150@psf.upfronthosting.co.za>
2017-04-25 09:05:45	vstinner	link	issue30150 messages
2017-04-25 09:05:45	vstinner	create