From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from dpdk.org (dpdk.org [92.243.14.124]) by inbox.dpdk.org (Postfix) with ESMTP id DE7BDA04C7; Wed, 16 Sep 2020 13:47:17 +0200 (CEST) Received: from [92.243.14.124] (localhost [127.0.0.1]) by dpdk.org (Postfix) with ESMTP id 6E41E1C246; Wed, 16 Sep 2020 13:47:17 +0200 (CEST) Received: from mga06.intel.com (mga06.intel.com [134.134.136.31]) by dpdk.org (Postfix) with ESMTP id BFAD11C23C for ; Wed, 16 Sep 2020 13:47:15 +0200 (CEST) IronPort-SDR: oyqEa5f5PfxU5oIByCkdNV9o6uGwyldavEBa6oovAivCk2274Ka0C+hPWkIHgmfaQK6g5PsaRE OiTwi8BtjHAg== X-IronPort-AV: E=McAfee;i="6000,8403,9745"; a="221002477" X-IronPort-AV: E=Sophos;i="5.76,432,1592895600"; d="scan'208";a="221002477" X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga004.jf.intel.com ([10.7.209.38]) by orsmga104.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 16 Sep 2020 04:47:14 -0700 IronPort-SDR: FvLkyGuSYAiWJVhYTxhEXr7Pwn6JRYLbWszChWHt/fgsdMlwSpbLbDZAqAiB/rXu4cWyMNnAza +fSPWuHQMw0Q== X-IronPort-AV: E=Sophos;i="5.76,432,1592895600"; d="scan'208";a="451823295" Received: from aburakov-mobl.ger.corp.intel.com (HELO [10.213.216.44]) ([10.213.216.44]) by orsmga004-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 16 Sep 2020 04:47:13 -0700 From: "Burakov, Anatoly" To: Kamaraj P Cc: Bruce Richardson , dev@dpdk.org References: <20200710102837.GB684@bricha3-MOBL.ger.corp.intel.com> <75824075-9690-814a-1849-1107504ce344@intel.com> <0b3a544d-4765-b284-1755-8b95eb86725d@intel.com> Message-ID: <4defb35b-ba04-6629-e740-2a47fa0fb121@intel.com> Date: Wed, 16 Sep 2020 12:47:12 +0100 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.12.0 MIME-Version: 1.0 In-Reply-To: <0b3a544d-4765-b284-1755-8b95eb86725d@intel.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Subject: Re: [dpdk-dev] DPDK hugepage memory fragmentation 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: , Errors-To: dev-bounces@dpdk.org Sender: "dev" On 16-Sep-20 12:19 PM, Burakov, Anatoly wrote: > On 16-Sep-20 5:32 AM, Kamaraj P wrote: >> Hi Anatoly, >> >> We just dump the memory contents when it fails to allocate the memory. >> > > Hi Kamaraj, > > Yes, i can see that the memory is fragmented. That's not what i was > asking though, because memory fragmentation is *expected* if you're > using igb_uio. You're not using VFIO and IOVA as VA addressing, so > you're at the mercy of your kernel when it comes to getting > IOVA-contiguous address. We in DPDK cannot do anything about it, because > we don't control which pages we get and what addresses they get > assigned. There's nothing to fix on our side in this situation. > > Here are the things you can do to avoid allocation failure in your case: > > 1) Drop the IOVA-contiguous allocation flag [1] > 2) Use legacy mode [2] [3] > 3) Switch to using VFIO [4] > 4) Use bigger page size > > The first point is crucial! Your allocation *wouldn't have failed* if > your code didn't specify for the allocation to require > IOVA-contiguousness. The fact that it has failed means that your > allocation has requested such memory, so it's on you to ensure that > whatever you're allocating, IOVA-contiguousness is *required*. I cannot > decide that for you as it is your code, so it is up to you to figure out > if whatever you're allocating actually requires such memory, or if you > can safely remove this allocation flag from your code. > > [1] > http://doc.dpdk.org/api/rte__memzone_8h.html#a3ccbea77ccab608c6e683817a3eb170f > > [2] > http://doc.dpdk.org/guides/prog_guide/env_abstraction_layer.html#memory-mapping-discovery-and-memory-reservation > > [3] http://doc.dpdk.org/guides/linux_gsg/linux_eal_parameters.html#id3 > [4] I understand the requirement for PF driver, but i think support for > PF in VFIO is coming in 20.11 release > Also, to add to this, we still haven't established that the allocation error is in fact due to memory fragmentation. You *claim* that is the case, but memory allocations can fail for other reasons, and you haven't provided me with anything that would confirm this, as *merely* the fact that the memory is fragmented will not, in and of itself, necessarily cause any allocation failures *unless* you are trying to allocate memory area that is bigger than your page size *and* is required to be contiguous. If you can't tell me *what* you're allocating, at least tell me the size of the allocation, the memzone flags it is allocated with, and any debug log messages around the allocation, so that we can at least be sure that we know the reason why the allocation fails. You're forcing me to fly blind here, i can't help you if i don't know what i'm dealing with. -- Thanks, Anatoly