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 64EE33989 for ; Wed, 9 Mar 2016 18:49:52 +0100 (CET) Received: from was59-1-82-226-113-214.fbx.proxad.net ([82.226.113.214] helo=[192.168.0.10]) by mail.droids-corp.org with esmtpsa (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.84) (envelope-from ) id 1adiGa-00067j-Do; Wed, 09 Mar 2016 18:51:24 +0100 To: Stephen Hemminger , dev@dpdk.org References: <1457490571-24429-1-git-send-email-stephen@networkplumber.org> From: Olivier MATZ X-Enigmail-Draft-Status: N1110 Message-ID: <56E06239.3060008@6wind.com> Date: Wed, 9 Mar 2016 18:49:45 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Icedove/38.6.0 MIME-Version: 1.0 In-Reply-To: <1457490571-24429-1-git-send-email-stephen@networkplumber.org> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Subject: Re: [dpdk-dev] [PATCH] mempool: avoid memory waste with large pagesize X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: patches and discussions about DPDK List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 09 Mar 2016 17:49:52 -0000 On 03/09/2016 03:29 AM, Stephen Hemminger wrote: > If page size is large (like 64K on ARM) and object size is small > then don't waste lots of memory by rounding up to page size. > Instead, round up so that 1 or more objects all fit in a page. > > This preserves the requirement that an object must not a page > or virt2phys would break, and makes sure 62K is not wasted per mbuf. You should specify that it only affects runs with "--no-huge". > --- a/lib/librte_mempool/rte_mempool.c > +++ b/lib/librte_mempool/rte_mempool.c > @@ -300,18 +300,24 @@ rte_mempool_calc_obj_size(uint32_t elt_size, uint32_t flags, > if (! rte_eal_has_hugepages()) { > /* > * compute trailer size so that pool elements fit exactly in > - * a standard page > + * a standard page. If elements are smaller than a page > + * then allow multiple elements per page > */ > - int page_size = getpagesize(); > - int new_size = page_size - sz->header_size - sz->elt_size; > - if (new_size < 0 || (unsigned int)new_size < sz->trailer_size) { > + unsigned page_size = getpagesize(); > + uint32_t orig_size, new_size; > + > + orig_size = sz->header_size + sz->elt_size; > + new_size = rte_align32pow2(orig_size); > + if (new_size > page_size) { > printf("When hugepages are disabled, pool objects " > "can't exceed PAGE_SIZE: %d + %d + %d > %d\n", > sz->header_size, sz->elt_size, sz->trailer_size, > page_size); > return 0; > } > - sz->trailer_size = new_size; > + > + sz->trailer_size = (new_size - orig_size) > + / (page_size / new_size); > } Looks it does not work, did I miss something? Examples: # start with --no-huge mp = rte_mempool_create("test", 128, 35, 0, 0, NULL, NULL, NULL, NULL, SOCKET_ID_ANY, 0); rte_mempool_dump(stdout, mp); shows: header_size=64 elt_size=40 trailer_size=0 total_obj_size=104 <<<<< should be 128? # start with --no-huge mp = rte_mempool_create("test", 128, 191, 0, 0, NULL, NULL, NULL, NULL, SOCKET_ID_ANY, MEMPOOL_F_NO_CACHE_ALIGN); rte_mempool_dump(stdout, mp); shows: header_size=8 elt_size=192 trailer_size=3 total_obj_size=203 <<<<< should be 256? The RFC I've just submitted also aims to fix this issue (but differently). Regards, Olivier