From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.droids-corp.org (zoll.droids-corp.org [94.23.50.67]) by dpdk.org (Postfix) with ESMTP id 247983255 for ; Mon, 4 Sep 2017 18:20:47 +0200 (CEST) Received: from lfbn-1-18623-73.w90-103.abo.wanadoo.fr ([90.103.154.73] helo=droids-corp.org) by mail.droids-corp.org with esmtpsa (TLS1.0:RSA_AES_256_CBC_SHA1:256) (Exim 4.84_2) (envelope-from ) id 1douCa-0008Q4-GH; Mon, 04 Sep 2017 18:26:22 +0200 Received: by droids-corp.org (sSMTP sendmail emulation); Mon, 04 Sep 2017 18:20:39 +0200 Date: Mon, 4 Sep 2017 18:20:39 +0200 From: Olivier MATZ To: Santosh Shukla Cc: dev@dpdk.org, thomas@monjalon.net, jerin.jacob@caviumnetworks.com, hemant.agrawal@nxp.com Message-ID: <20170904162038.irmqwqqyzflbz7zv@neon> References: <20170720134759.4680-1-santosh.shukla@caviumnetworks.com> <20170815060743.21076-1-santosh.shukla@caviumnetworks.com> <20170815060743.21076-7-santosh.shukla@caviumnetworks.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170815060743.21076-7-santosh.shukla@caviumnetworks.com> User-Agent: NeoMutt/20170113 (1.7.2) Subject: Re: [dpdk-dev] [PATCH v4 6/7] mempool: introduce block size align flag X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 04 Sep 2017 16:20:47 -0000 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. 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. > - 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.