Re: malloc, thread and alignment

[Joerg Sonnenberger <joerg%britannica.bec.de@localhost>]

On Fri, Mar 27, 2015 at 04:38:56PM +0000, Taylor R Campbell wrote:
> Someone^TM should document the kernel CACHE_LINE_SIZE, coherency_unit,
> COHERENCY_UNIT, and figure out what it is worthwhile to expose MI to
> userland.  Obviously some systems may have different instruction and
> data cache line sizes, and maybe there are more exotic possibilities,
> but presumably there is a good conservative estimate for user programs
> to round buffers to.  jemalloc seems to use 64 bytes unconditionally.

How much sense does it really make to change the alignment size of an
allocation without understanding the data structure inside? Chance are
if you have cache-critical small allocations, you have been doing
something wrong already.

Joerg