From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755365Ab2LLVsK (ORCPT ); Wed, 12 Dec 2012 16:48:10 -0500 Received: from mga11.intel.com ([192.55.52.93]:31180 "EHLO mga11.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755168Ab2LLVsI (ORCPT ); Wed, 12 Dec 2012 16:48:08 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.84,269,1355126400"; d="scan'208";a="263186475" Message-ID: <50C8FB94.6050209@linux.intel.com> Date: Wed, 12 Dec 2012 13:48:04 -0800 From: "H. Peter Anvin" User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/17.0 Thunderbird/17.0 MIME-Version: 1.0 To: Andrew Morton CC: "Kirill A. Shutemov" , David Rientjes , Andrea Arcangeli , linux-mm@kvack.org, Andi Kleen , linux-kernel@vger.kernel.org, "Kirill A. Shutemov" Subject: Re: [PATCH v5 09/11] thp: lazy huge zero page allocation References: <1352300463-12627-1-git-send-email-kirill.shutemov@linux.intel.com> <1352300463-12627-10-git-send-email-kirill.shutemov@linux.intel.com> <20121115094155.GG9676@otc-wbsnb-06> <20121212133051.6dad3722.akpm@linux-foundation.org> In-Reply-To: <20121212133051.6dad3722.akpm@linux-foundation.org> 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 12/12/2012 01:30 PM, Andrew Morton wrote: >> >> I can rewrite the check to static_key if you want. Would it be better? > > The new test-n-branch only happens on the first read fault against a > thp huge page, yes? In which case it's a quite infrequent event and I > suspect this isn't worth bothering about. > Not to mention that flipping the static key is *incredibly* expensive. -hpa