From mboxrd@z Thu Jan 1 00:00:00 1970 From: Thomas Monjalon Subject: Re: [PATCH 9/9] memalloc: allocate memory in reverse Date: Tue, 24 Jul 2018 12:24:40 +0200 Message-ID: <5303347.Rbc4TJUbQV@xps> References: <914a5f584be81d6c129b35bc8e358774854d8960.1528749451.git.anatoly.burakov@intel.com> <1f5ef2a7-739e-b90f-8b04-a2a0abe234fa@intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7Bit Cc: dev@dpdk.org To: "Burakov, Anatoly" Return-path: Received: from out1-smtp.messagingengine.com (out1-smtp.messagingengine.com [66.111.4.25]) by dpdk.org (Postfix) with ESMTP id 5364B98 for ; Tue, 24 Jul 2018 12:24:46 +0200 (CEST) In-Reply-To: <1f5ef2a7-739e-b90f-8b04-a2a0abe234fa@intel.com> List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces@dpdk.org Sender: "dev" 24/07/2018 12:10, Burakov, Anatoly: > On 11-Jun-18 9:55 PM, Anatoly Burakov wrote: > > Currently, all hugepages are allocated from lower VA address to > > higher VA address, while malloc heap allocates from higher VA > > address to lower VA address. This results in heap fragmentation > > over time due to multiple reserves leaving small space below the > > allocated elements. > > > > Fix this by allocating VA memory from the top, thereby reducing > > fragmentation and lowering overall memory usage. > > > > Signed-off-by: Anatoly Burakov > > --- > > lib/librte_eal/linuxapp/eal/eal_memalloc.c | 3 ++- > > 1 file changed, 2 insertions(+), 1 deletion(-) > > > > diff --git a/lib/librte_eal/linuxapp/eal/eal_memalloc.c b/lib/librte_eal/linuxapp/eal/eal_memalloc.c > > index 8c11f98c9..d35fb52c4 100644 > > --- a/lib/librte_eal/linuxapp/eal/eal_memalloc.c > > +++ b/lib/librte_eal/linuxapp/eal/eal_memalloc.c > > @@ -682,7 +682,8 @@ alloc_seg_walk(const struct rte_memseg_list *msl, void *arg) > > need = wa->n_segs; > > > > /* try finding space in memseg list */ > > - cur_idx = rte_fbarray_find_next_n_free(&cur_msl->memseg_arr, 0, need); > > + cur_idx = rte_fbarray_find_prev_n_free(&cur_msl->memseg_arr, > > + cur_msl->memseg_arr.len - 1, need); > > if (cur_idx < 0) > > return 0; > > start_idx = cur_idx; > > > > Hi Thomas, > > We have discovered a few regressions in virtio/vhost use cases due to > this patch. Virtio expects to map all segments starting from 0 address, > and this patch breaks that assumption. > > Can we revert this for 18.08? It will be reintroduced in 18.11 along > with fixes for virtio/vhost fixes to account for this change. Yes, please send the patch with explanations.