this 48-core box...

[Eduardo Morras]

On Sat, 21 Sep 2013 12:53:36 -0700
Adrian Chadd <adrian at freebsd.org> wrote:

> .. just as a data point - there was a thread a while ago about numeric
> processing performance on linux vs bsd.
> 
> It all boiled down to how jemalloc versus the linux allocator(s) allocate
> blocks. jemalloc will page align things after a certain size. Linux didn't.
> So when doing numeric processing, there was a lot of cache aliasing going
> on leading to inefficient cache usage and redundant memory operations.
> 
> When the same workload on Linux was run on FreeBSD but with the Linux
> library/allocators, the performance was identical.
> 
> No-one followed through. I think I may have to write a blog post about it.

There's no MALLOC_OPTIONS flag to set/unset this, but adding a new flag to disable a feature is easier (or should be) than implementing new one. The only problem I see to this is if the cache align happens at sbrk/mmap level.

 
> 
> -adrian
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Eduardo Morras <emorrasg at yahoo.es>