From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mga01.intel.com (mga01.intel.com [192.55.52.88]) by dpdk.org (Postfix) with ESMTP id 1210D5A85 for ; Thu, 23 Jul 2015 09:34:45 +0200 (CEST) Received: from fmsmga001.fm.intel.com ([10.253.24.23]) by fmsmga101.fm.intel.com with ESMTP; 23 Jul 2015 00:34:45 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.15,529,1432623600"; d="scan'208";a="752904952" Received: from smonroyx-mobl.ger.corp.intel.com (HELO [10.237.221.12]) ([10.237.221.12]) by fmsmga001.fm.intel.com with ESMTP; 23 Jul 2015 00:34:44 -0700 Message-ID: <55B09913.8040100@intel.com> Date: Thu, 23 Jul 2015 08:34:43 +0100 From: "Gonzalez Monroy, Sergio" User-Agent: Mozilla/5.0 (Windows NT 6.3; WOW64; rv:31.0) Gecko/20100101 Thunderbird/31.7.0 MIME-Version: 1.0 To: Thomas Monjalon References: <3797202.NyZr8XgqE1@xps13> In-Reply-To: <3797202.NyZr8XgqE1@xps13> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Cc: dev@dpdk.org Subject: Re: [dpdk-dev] libhugetlbfs 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: Thu, 23 Jul 2015 07:34:46 -0000 On 22/07/2015 11:40, Thomas Monjalon wrote: > Sergio, > > As the maintainer of memory allocation, would you consider using > libhugetlbfs in DPDK for Linux? > It may simplify a part of our memory allocator and avoid some potential > bugs which would be already fixed in the dedicated lib. I did have a look at it a couple of months ago and I thought there were a few issues: - get_hugepage_region/get_huge_pages only allocates default size huge pages (you can set a different default huge page size with environment variables but no support for multiple sizes) plus we have no guarantee on physically contiguous pages. - That leave us with hugetlbfs_unlinked_fd/hugetlbfs_unlinked_fd_for_size. These APIs wouldn't simplify a lot the current code, just the allocation of the pages themselves (ie. creating a file in hugetlbfs mount). Then there is the issue with multi-process; because they return a file descriptor while unlinking the file, we would need some sort of Inter-Process Communication to pass the descriptors to secondary processes. - Not a big deal but AFAIK it is not possible to have multiple mount points for the same hugepage size, and even if you do, hugetlbfs_find_path_for_size returns always the same path (ie. first found in list). - We still need to parse /proc/self/pagemap to get physical address of mapped hugepages. I guess that if we were to push for a new API such as hugetlbfs_fd_for_size, we could use it for the hugepage allocation, but we still would have to parse /proc/self/pagemap to get physical address and then order those hugepages. Thoughts? Sergio