From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andi Kleen Subject: Re: [PATCH 0/3] Virtual huge zero page Date: Sat, 29 Sep 2012 07:30:06 -0700 Message-ID: <20120929143006.GC4110@tassilo.jf.intel.com> References: <1348875441-19561-1-git-send-email-kirill.shutemov@linux.intel.com> <20120929134811.GC26989@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from mga09.intel.com ([134.134.136.24]:57289 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752371Ab2I2OaG (ORCPT ); Sat, 29 Sep 2012 10:30:06 -0400 Content-Disposition: inline In-Reply-To: <20120929134811.GC26989@redhat.com> Sender: linux-arch-owner@vger.kernel.org List-ID: To: Andrea Arcangeli Cc: "Kirill A. Shutemov" , Andrew Morton , linux-mm@kvack.org, "H. Peter Anvin" , linux-kernel@vger.kernel.org, "Kirill A. Shutemov" , Arnd Bergmann , Ingo Molnar , linux-arch@vger.kernel.org On Sat, Sep 29, 2012 at 03:48:11PM +0200, Andrea Arcangeli wrote: > On Sat, Sep 29, 2012 at 02:37:18AM +0300, Kirill A. Shutemov wrote: > > Cons: > > - increases TLB pressure; > > I generally don't like using 4k tlb entries ever. This only has the >From theory I would also prefer the 2MB huge page. But some numbers comparing between the two alternatives are definitely interesting. Numbers are often better than theory. > There would be a small cache benefit here... but even then some first > level caches are virtually indexed IIRC (always physically tagged to Modern x86 doesn't have virtually indexed caches. -Andi -- ak@linux.intel.com -- Speaking for myself only From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx173.postini.com [74.125.245.173]) by kanga.kvack.org (Postfix) with SMTP id 3ADD16B006C for ; Sat, 29 Sep 2012 10:30:07 -0400 (EDT) Date: Sat, 29 Sep 2012 07:30:06 -0700 From: Andi Kleen Subject: Re: [PATCH 0/3] Virtual huge zero page Message-ID: <20120929143006.GC4110@tassilo.jf.intel.com> References: <1348875441-19561-1-git-send-email-kirill.shutemov@linux.intel.com> <20120929134811.GC26989@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20120929134811.GC26989@redhat.com> Sender: owner-linux-mm@kvack.org List-ID: To: Andrea Arcangeli Cc: "Kirill A. Shutemov" , Andrew Morton , linux-mm@kvack.org, "H. Peter Anvin" , linux-kernel@vger.kernel.org, "Kirill A. Shutemov" , Arnd Bergmann , Ingo Molnar , linux-arch@vger.kernel.org On Sat, Sep 29, 2012 at 03:48:11PM +0200, Andrea Arcangeli wrote: > On Sat, Sep 29, 2012 at 02:37:18AM +0300, Kirill A. Shutemov wrote: > > Cons: > > - increases TLB pressure; > > I generally don't like using 4k tlb entries ever. This only has the >>From theory I would also prefer the 2MB huge page. But some numbers comparing between the two alternatives are definitely interesting. Numbers are often better than theory. > There would be a small cache benefit here... but even then some first > level caches are virtually indexed IIRC (always physically tagged to Modern x86 doesn't have virtually indexed caches. -Andi -- ak@linux.intel.com -- Speaking for myself only -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754821Ab2I2OaJ (ORCPT ); Sat, 29 Sep 2012 10:30:09 -0400 Received: from mga09.intel.com ([134.134.136.24]:57289 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752371Ab2I2OaG (ORCPT ); Sat, 29 Sep 2012 10:30:06 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.80,507,1344236400"; d="scan'208";a="199695574" Date: Sat, 29 Sep 2012 07:30:06 -0700 From: Andi Kleen To: Andrea Arcangeli Cc: "Kirill A. Shutemov" , Andrew Morton , linux-mm@kvack.org, "H. Peter Anvin" , linux-kernel@vger.kernel.org, "Kirill A. Shutemov" , Arnd Bergmann , Ingo Molnar , linux-arch@vger.kernel.org Subject: Re: [PATCH 0/3] Virtual huge zero page Message-ID: <20120929143006.GC4110@tassilo.jf.intel.com> References: <1348875441-19561-1-git-send-email-kirill.shutemov@linux.intel.com> <20120929134811.GC26989@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20120929134811.GC26989@redhat.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, Sep 29, 2012 at 03:48:11PM +0200, Andrea Arcangeli wrote: > On Sat, Sep 29, 2012 at 02:37:18AM +0300, Kirill A. Shutemov wrote: > > Cons: > > - increases TLB pressure; > > I generally don't like using 4k tlb entries ever. This only has the >>From theory I would also prefer the 2MB huge page. But some numbers comparing between the two alternatives are definitely interesting. Numbers are often better than theory. > There would be a small cache benefit here... but even then some first > level caches are virtually indexed IIRC (always physically tagged to Modern x86 doesn't have virtually indexed caches. -Andi -- ak@linux.intel.com -- Speaking for myself only