Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751696AbaJTMCv (ORCPT ); Mon, 20 Oct 2014 08:02:51 -0400 Received: from mail-wg0-f44.google.com ([74.125.82.44]:52626 "EHLO mail-wg0-f44.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751526AbaJTMCt (ORCPT ); Mon, 20 Oct 2014 08:02:49 -0400 Date: Mon, 20 Oct 2014 14:02:43 +0200 From: Ingo Molnar To: Daniel J Blueman Cc: Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , Bjorn Helgaas , x86@kernel.org, linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org, Steffen Persvold Subject: Re: [PATCH v2 5/5] Numachip: use 2GB memory block size Message-ID: <20141020120243.GA13186@gmail.com> References: <1413683152-31302-1-git-send-email-daniel@numascale.com> <1413683152-31302-5-git-send-email-daniel@numascale.com> <20141019092324.GA10027@gmail.com> <5444B3DC.90709@numascale.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <5444B3DC.90709@numascale.com> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Daniel J Blueman wrote: > On 19/10/2014 17:23, Ingo Molnar wrote: > > > >* Daniel J Blueman wrote: > > > >>Use appropriate memory block size to reduce sysfs entry creation time > >>by 16x. > >> > >>Boot-tested with the four permutations of X86_UV and X86_NUMACHIP. > >> > >>Signed-off-by: Daniel J Blueman > >>--- > >> arch/x86/mm/init_64.c | 7 ++++--- > >> 1 file changed, 4 insertions(+), 3 deletions(-) > >> > >>diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c > >>index 5621c47..22ea6de 100644 > >>--- a/arch/x86/mm/init_64.c > >>+++ b/arch/x86/mm/init_64.c > >>@@ -53,6 +53,7 @@ > >> #include > >> #include > >> #include > >>+#include > >> #include > >> > >> #include "mm_internal.h" > >>@@ -1235,9 +1236,9 @@ static unsigned long probe_memory_block_size(void) > >> /* start from 2g */ > >> unsigned long bz = 1UL<<31; > >> > >>-#ifdef CONFIG_X86_UV > >>- if (is_uv_system()) { > >>- printk(KERN_INFO "UV: memory block size 2GB\n"); > >>+#ifdef CONFIG_X86_64 > >>+ if (is_uv_system() || is_numachip_system()) { > >>+ pr_info("Memory block size 2GB for large-SMP system\n"); > >> return 2UL * 1024 * 1024 * 1024; > > > >It would be a lot cleaner and more robust to have a more > >intelligent decision here. > > > >Is there a reliable indicator for large 'sysfs entry creation > >time', such as a lot of RAM present? > > Yes, agreed exactly. > > > Also, it would be nice to list the pros/cons of this change, > > an advantage is reduced overhead - what are the > > disadvantages? > > The single disadvantage is that small-memory systems won't be > able to have finer control of memory offlining, though the > impact of that depend on why the user is offlining memory of > course. > > If it seems reasonable for x86-64 systems with >64GB memory to > have 2GB memory block sizes, I could prepare that change > instead and document the above if preferred? I'd make it >= 64GB, but yes, that sounds like a good limit. Thanks, Ingo -- 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/