Re: [dpdk-dev] [PATCH v4] mempool: remove memory wastage on non x86

[Olivier Matz <olivier.matz@6wind.com>]

On Thu, Jan 16, 2020 at 06:40:23PM +0530, Jerin Jacob wrote:
> On Wed, Jan 15, 2020 at 2:35 AM <jerinj@marvell.com> wrote:
> >
> > From: Jerin Jacob <jerinj@marvell.com>
> >
> > The existing optimize_object_size() function address the memory object
> > alignment constraint on x86 for better performance.
> >
> > Different (micro) architecture may have different memory alignment
> > constraint for better performance and it not the same as the existing
> > optimize_object_size().
> >
> > Some use, XOR(kind of CRC) scheme to enable DRAM channel distribution
> > based on the address and some may have a different formula.
> >
> > Introducing arch_mem_object_align() function to abstract
> > the difference between different (micro) architectures to avoid
> > wasting memory for mempool object alignment for the architecture
> > that it is not required to do so.
> >
> > Details on the amount of memory saving:
> >
> > Currently, arm64 based architectures use the default (nchan=4,
> > nrank=1). The worst case is for an object whose size (including mempool
> > header) is 2 cache lines, where it is optimized to 3 cache lines (+50%).
> >
> > Examples for cache lines size = 64:
> >   orig     optimized
> >   64    -> 64           +0%
> >   128   -> 192          +50%
> >   192   -> 192          +0%
> >   256   -> 320          +25%
> >   320   -> 320          +0%
> >   384   -> 448          +16%
> >   ...
> >   2304  -> 2368         +2.7%  (~mbuf size)
> >
> > Additional details:
> > https://www.mail-archive.com/dev@dpdk.org/msg149157.html
> >
> > Signed-off-by: Jerin Jacob <jerinj@marvell.com>
> > Reviewed-by: Gavin Hu <gavin.hu@arm.com>
> 
> Ping for merge.

Acked-by: Olivier Matz <olivier.matz@6wind.com>