From mboxrd@z Thu Jan 1 00:00:00 1970 From: santosh Subject: Re: [PATCH v4 6/7] mempool: introduce block size align flag Date: Mon, 4 Sep 2017 23:15:50 +0530 Message-ID: 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=windows-1252 Content-Transfer-Encoding: 7bit Cc: dev@dpdk.org, thomas@monjalon.net, jerin.jacob@caviumnetworks.com, hemant.agrawal@nxp.com To: Olivier MATZ Return-path: Received: from NAM03-CO1-obe.outbound.protection.outlook.com (mail-co1nam03on0067.outbound.protection.outlook.com [104.47.40.67]) by dpdk.org (Postfix) with ESMTP id 2C6357CA9 for ; Mon, 4 Sep 2017 19:46:14 +0200 (CEST) In-Reply-To: <20170904162038.irmqwqqyzflbz7zv@neon> 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 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.