Re: [PATCH RFC 1/2] scatterlist: add mempool based chained SG alloc/free api

[Ming Lin <mlin@kernel.org>]

On Wed, 2016-03-16 at 09:23 +0100, Christoph Hellwig wrote:
> > 
> We can defintively kill this one.

We want to support different size of pools.
How can we kill this one?

Or did you mean we just create a single pool with size SG_CHUNK_SIZE?

> 
> > +static __init int sg_mempool_init(void)
> > +{
> > +	int i;
> > +
> > +	for (i = 0; i < SG_MEMPOOL_NR; i++) {
> > +		struct sg_mempool *sgp = sg_pools + i;
> > +		int size = sgp->size * sizeof(struct scatterlist);
> > +
> > +		sgp->slab = kmem_cache_create(sgp->name, size, 0,
> > +				SLAB_HWCACHE_ALIGN, NULL);
> 
> Having these mempoools around in every kernel will make some embedded
> developers rather unhappy.  We could either not create them at
> runtime, which would require either a check in the fast path, or
> an init call in every driver, or just move the functions you
> added into a separe file, which will be compiled only based on a
> Kconfig
> symbol, and could even be potentially modular.  I think that
> second option might be easier.

I created lib/sg_pool.c with CONFIG_SG_POOL.