From mboxrd@z Thu Jan 1 00:00:00 1970 From: Olivier MATZ Subject: Re: [PATCH v4 6/7] mempool: introduce block size align flag Date: Thu, 7 Sep 2017 09:27:25 +0200 Message-ID: <20170907072724.fixbpyxby4eprzt5@neon> References: <20170720134759.4680-1-santosh.shukla@caviumnetworks.com> <20170815060743.21076-1-santosh.shukla@caviumnetworks.com> <20170815060743.21076-7-santosh.shukla@caviumnetworks.com> <20170904162038.irmqwqqyzflbz7zv@neon> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: dev@dpdk.org, thomas@monjalon.net, jerin.jacob@caviumnetworks.com, hemant.agrawal@nxp.com To: santosh Return-path: Received: from mail.droids-corp.org (zoll.droids-corp.org [94.23.50.67]) by dpdk.org (Postfix) with ESMTP id 55E2D16829 for ; Thu, 7 Sep 2017 09:27:33 +0200 (CEST) Content-Disposition: inline In-Reply-To: List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces@dpdk.org Sender: "dev" On Mon, Sep 04, 2017 at 11:15:50PM +0530, santosh wrote: > > On Monday 04 September 2017 09:50 PM, Olivier MATZ wrote: > > On Tue, Aug 15, 2017 at 11:37:42AM +0530, Santosh Shukla wrote: > >> Some mempool hw like octeontx/fpa block, demands block size > >> (/total_elem_sz) aligned object start address. > >> > >> Introducing an MEMPOOL_F_POOL_BLK_SZ_ALIGNED flag. > >> If this flag is set: > >> - Align object start address to a multiple of total_elt_sz. > > Please specify if it's virtual or physical address. > > virtual address. Yes will mention in v5. Thanks. > > > What do you think about MEMPOOL_F_BLK_ALIGNED_OBJECTS instead? > > > > I don't really like BLK because the word "block" is not used anywhere > > else in the mempool code. But I cannot find any good replacement for > > it. If you have another idea, please suggest. > > > Ok with renaming to MEMPOOL_F_BLK_ALIGNED_OBJECTS > > >> - Allocate one additional object. Additional object is needed to make > >> sure that requested 'n' object gets correctly populated. Example: > >> > >> - Let's say that we get 'x' size of memory chunk from memzone. > >> - And application has requested 'n' object from mempool. > >> - Ideally, we start using objects at start address 0 to...(x-block_sz) > >> for n obj. > >> - Not necessarily first object address i.e. 0 is aligned to block_sz. > >> - So we derive 'offset' value for block_sz alignment purpose i.e..'off'. > >> - That 'off' makes sure that start address of object is blk_sz > >> aligned. > >> - Calculating 'off' may end up sacrificing first block_sz area of > >> memzone area x. So total number of the object which can fit in the > >> pool area is n-1, Which is incorrect behavior. > >> > >> Therefore we request one additional object (/block_sz area) from memzone > >> when F_BLK_SZ_ALIGNED flag is set. > >> > >> Signed-off-by: Santosh Shukla > >> Signed-off-by: Jerin Jacob > >> --- > >> lib/librte_mempool/rte_mempool.c | 16 +++++++++++++--- > >> lib/librte_mempool/rte_mempool.h | 1 + > >> 2 files changed, 14 insertions(+), 3 deletions(-) > >> > >> diff --git a/lib/librte_mempool/rte_mempool.c b/lib/librte_mempool/rte_mempool.c > >> index 19e5e6ddf..7610f0d1f 100644 > >> --- a/lib/librte_mempool/rte_mempool.c > >> +++ b/lib/librte_mempool/rte_mempool.c > >> @@ -239,10 +239,14 @@ rte_mempool_calc_obj_size(uint32_t elt_size, uint32_t flags, > >> */ > >> size_t > >> rte_mempool_xmem_size(uint32_t elt_num, size_t total_elt_sz, uint32_t pg_shift, > >> - __rte_unused const struct rte_mempool *mp) > >> + const struct rte_mempool *mp) > >> { > >> size_t obj_per_page, pg_num, pg_sz; > >> > >> + if (mp && mp->flags & MEMPOOL_F_POOL_BLK_SZ_ALIGNED) > >> + /* alignment need one additional object */ > >> + elt_num += 1; > >> + > >> if (total_elt_sz == 0) > >> return 0; > > I'm wondering if it's correct if the mempool area is not contiguous. > > > > For instance: > > page size = 4096 > > object size = 1900 > > elt_num = 10 > > > > With your calculation, you will request (11+2-1)/2 = 6 pages. > > But actually you may need 10 pages (max), since the number of object per > > page matching the alignement constraint is 1, not 2. > > > In our case, we set PMD flag MEMPOOL_F_CAPA_PHYS_CONTIG to detect contiguity, > would fail at pool creation time, as HW don't support. Yes but here it's generic code. If MEMPOOL_F_POOL_BLK_SZ_ALIGNED implies MEMPOOL_F_CAPA_PHYS_CONTIG, it should be enforced somewhere.