[dpdk-dev] [PATCH 1/5] mempool: allow unaligned addr/len in populate virt

[Olivier Matz]

Hi Andrew,

On Tue, Oct 29, 2019 at 12:21:27PM +0300, Andrew Rybchenko wrote:
> On 10/28/19 5:01 PM, Olivier Matz wrote:
> > rte_mempool_populate_virt() currently requires that both addr
> > and length are page-aligned.
> > 
> > Remove this uneeded constraint which can be annoying with big
> > hugepages (ex: 1GB).
> > 
> > Signed-off-by: Olivier Matz <olivier.matz at 6wind.com>
> 
> One note below, other than that
> Reviewed-by: Andrew Rybchenko <arybchenko at solarflare.com>
> 
> > ---
> >   lib/librte_mempool/rte_mempool.c | 18 +++++++-----------
> >   lib/librte_mempool/rte_mempool.h |  3 +--
> >   2 files changed, 8 insertions(+), 13 deletions(-)
> > 
> > diff --git a/lib/librte_mempool/rte_mempool.c b/lib/librte_mempool/rte_mempool.c
> > index 0f29e8712..76cbacdf3 100644
> > --- a/lib/librte_mempool/rte_mempool.c
> > +++ b/lib/librte_mempool/rte_mempool.c
> > @@ -368,17 +368,11 @@ rte_mempool_populate_virt(struct rte_mempool *mp, char *addr,
> >   	size_t off, phys_len;
> >   	int ret, cnt = 0;
> > -	/* address and len must be page-aligned */
> > -	if (RTE_PTR_ALIGN_CEIL(addr, pg_sz) != addr)
> > -		return -EINVAL;
> > -	if (RTE_ALIGN_CEIL(len, pg_sz) != len)
> > -		return -EINVAL;
> > -
> >   	if (mp->flags & MEMPOOL_F_NO_IOVA_CONTIG)
> >   		return rte_mempool_populate_iova(mp, addr, RTE_BAD_IOVA,
> >   			len, free_cb, opaque);
> > -	for (off = 0; off + pg_sz <= len &&
> > +	for (off = 0; off < len &&
> >   		     mp->populated_size < mp->size; off += phys_len) {
> >   		iova = rte_mem_virt2iova(addr + off);
> > @@ -389,7 +383,10 @@ rte_mempool_populate_virt(struct rte_mempool *mp, char *addr,
> >   		}
> >   		/* populate with the largest group of contiguous pages */
> > -		for (phys_len = pg_sz; off + phys_len < len; phys_len += pg_sz) {
> > +		for (phys_len = RTE_PTR_ALIGN_CEIL(addr + off + 1, pg_sz) -
> > +			     (addr + off);
> > +		     off + phys_len < len;
> 
> If the condition is false on the first check, below we'll populate memory
> outside of specified length. So, we should either apply MIN above when
> phys_len
> is initialized or drop MIN in the next line, but apply MIN when
> rte_mempool_populate_iova() is called.

Correct, I'll fix it by adding a RTE_MIN(). Maybe I'll just move it
outside of the for.

> Bonus question not directly related to the patch is iova == RTE_BAD_IOVA
> case when !rte_eal_has_hugepages():
> Is it expected that we still use arithmetic iova + phys_len in this case?
> I guess comparison will always be false and pages never merged, but it looks
> suspicious anyway.

Yes, this is not very elegant.
I can change the test to
	if (iova_tmp != RTE_BAD_IOVA || iova_tmp != iova + phys_len)

> 
> > +		     phys_len = RTE_MIN(phys_len + pg_sz, len - off)) {
> >   			rte_iova_t iova_tmp;
> >   			iova_tmp = rte_mem_virt2iova(addr + off + phys_len);
> > @@ -575,8 +572,7 @@ rte_mempool_populate_default(struct rte_mempool *mp)
> >   			 * have
> >   			 */
> >   			mz = rte_memzone_reserve_aligned(mz_name, 0,
> > -					mp->socket_id, flags,
> > -					RTE_MAX(pg_sz, align));
> > +					mp->socket_id, flags, align);
> >   		}
> >   		if (mz == NULL) {
> >   			ret = -rte_errno;
> > @@ -601,7 +597,7 @@ rte_mempool_populate_default(struct rte_mempool *mp)
> >   				(void *)(uintptr_t)mz);
> >   		else
> >   			ret = rte_mempool_populate_virt(mp, mz->addr,
> > -				RTE_ALIGN_FLOOR(mz->len, pg_sz), pg_sz,
> > +				mz->len, pg_sz,
> >   				rte_mempool_memchunk_mz_free,
> >   				(void *)(uintptr_t)mz);
> >   		if (ret < 0) {
> > diff --git a/lib/librte_mempool/rte_mempool.h b/lib/librte_mempool/rte_mempool.h
> > index 8053f7a04..0fe8aa7b8 100644
> > --- a/lib/librte_mempool/rte_mempool.h
> > +++ b/lib/librte_mempool/rte_mempool.h
> > @@ -1042,9 +1042,8 @@ int rte_mempool_populate_iova(struct rte_mempool *mp, char *vaddr,
> >    *   A pointer to the mempool structure.
> >    * @param addr
> >    *   The virtual address of memory that should be used to store objects.
> > - *   Must be page-aligned.
> >    * @param len
> > - *   The length of memory in bytes. Must be page-aligned.
> > + *   The length of memory in bytes.
> >    * @param pg_sz
> >    *   The size of memory pages in this virtual area.
> >    * @param free_cb
>