Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754186AbaFBQLk (ORCPT ); Mon, 2 Jun 2014 12:11:40 -0400 Received: from mga09.intel.com ([134.134.136.24]:60329 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752396AbaFBQLi (ORCPT ); Mon, 2 Jun 2014 12:11:38 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.98,957,1392192000"; d="scan'208";a="550287708" Message-ID: <538CA239.3060506@intel.com> Date: Mon, 02 Jun 2014 09:11:37 -0700 From: Dave Hansen User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.5.0 MIME-Version: 1.0 To: Naoya Horiguchi , Andrew Morton CC: Konstantin Khlebnikov , Wu Fengguang , Arnaldo Carvalho de Melo , Borislav Petkov , "Kirill A. Shutemov" , Johannes Weiner , Rusty Russell , David Miller , Andres Freund , linux-kernel@vger.kernel.org, linux-mm@kvack.org, "Kirill A. Shutemov" Subject: Re: [PATCH 2/3] mm: introduce fincore() References: <20140521193336.5df90456.akpm@linux-foundation.org> <1401686699-9723-1-git-send-email-n-horiguchi@ah.jp.nec.com> <1401686699-9723-3-git-send-email-n-horiguchi@ah.jp.nec.com> In-Reply-To: <1401686699-9723-3-git-send-email-n-horiguchi@ah.jp.nec.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 06/01/2014 10:24 PM, Naoya Horiguchi wrote: > Detail about the data format being passed to userspace are explained in > inline comment, but generally in long entry format, we can choose which > information is extraced flexibly, so you don't have to waste memory by > extracting unnecessary information. And with FINCORE_SKIP_HOLE flag, > we can skip hole pages (not on memory,) which makes us avoid a flood of > meaningless zero entries when calling on extremely large (but only few > pages of it are loaded on memory) file. Something similar could be useful for hugetlbfs too. For a 1GB page, it's pretty silly to do 2^18 entries which essentially repeat the same data in an interface like this. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/