Re: malloc, thread and alignment

["Jean-Yves Migeon (NetBSD)" <jym%NetBSD.org@localhost>]

Le 26/03/2015 15:13, Emmanuel Dreyfus a écrit :
> Hello
>
> jemmaloc(3) says:
>   Allocations are packed tightly together, which can be an issue for 
> multi-
>   threaded applications.  If you need to assure that allocations do not
>   suffer from cache line sharing, round your allocation requests up to 
> the
>   nearest multiple of the cache line size.
>
> Do we are example of how it should be done? I do not know how to 
> discover
> cache line size, neither do I know how I can specify alignment based on 
> it.

For x86 you can look at cpuctl(8), identifycpu() uses cpuid to get this 
information. This is MD and varies between AMD/Intel, revisions... This 
requires not-so-funny tests to deduce the correct value. I don't think 
this is exposed through headers/libs for external use though.

AFAICT !x86 platforms have nothing.

--
Jean-Yves Migeon
jym@