Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S936140AbXFFWDe (ORCPT ); Wed, 6 Jun 2007 18:03:34 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S934844AbXFFWD1 (ORCPT ); Wed, 6 Jun 2007 18:03:27 -0400 Received: from lucidpixels.com ([75.144.35.66]:46888 "EHLO lucidpixels.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934501AbXFFWD0 (ORCPT ); Wed, 6 Jun 2007 18:03:26 -0400 Date: Wed, 6 Jun 2007 18:03:25 -0400 (EDT) From: Justin Piszcz X-X-Sender: jpiszcz@p34.internal.lan To: Jesse Barnes cc: Andi Kleen , linux-kernel@vger.kernel.org, "Eric W. Biederman" Subject: Re: [PATCH] trim memory not covered by WB MTRRs In-Reply-To: Message-ID: References: <200706061229.24486.jesse.barnes@intel.com> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3301 Lines: 80 Mem: 8039620k total, 7936472k used, 103148k free, 708k buffers Mem: 8039608k total, 969380k used, 7070228k free, 1232k buffers I am curious, why does the patch != the mem=8832M? Justin. On Wed, 6 Jun 2007, Justin Piszcz wrote: > > > On Wed, 6 Jun 2007, Jesse Barnes wrote: > >> On some machines, buggy BIOSes don't properly setup WB MTRRs to >> cover all available RAM, meaning the last few megs (or even gigs) >> of memory will be marked uncached. Since Linux tends to allocate >> from high memory addresses first, this causes the machine to be >> unusably slow as soon as the kernel starts really using memory >> (i.e. right around init time). >> >> This patch works around the problem by scanning the MTRRs at >> boot and figuring out whether the current end_pfn value (setup >> by early e820 code) goes beyond the highest WB MTRR range, and >> if so, trimming it to match. A fairly obnoxious KERN_WARNING >> is printed too, letting the user know that not all of their >> memory is available due to a likely BIOS bug. >> >> Something similar could be done on i386 if needed, but the boot >> ordering would be slightly different, since the MTRR code on i386 >> depends on the boot_cpu_data structure being setup. >> >> Justin, can you please test and make sure this patch works for >> you too? It'll only work around the problem, but it's better >> than having to do mem= by hand or waiting for a fix from your >> BIOS vendor. >> >> Thanks, >> Jesse > > Jesse, it worked. > > With mem=8832M (without your patch): 2.6.22-rc4: > > top - 17:39:02 up 1 day, 8:07, 25 users, load average: 2.33, 0.76, 0.30 > Tasks: 325 total, 11 running, 314 sleeping, 0 stopped, 0 zombie > Cpu(s): 80.0%us, 20.0%sy, 0.0%ni, 0.0%id, 0.0%wa, 0.0%hi, 0.0%si, > 0.0%st > Mem: 8039620k total, 7936472k used, 103148k free, 708k buffers > Swap: 16787768k total, 128k used, 16787640k free, 6646248k cached > > With no mem= in append line (with your patch): 2.6.22-rc4: > > top - 17:44:01 up 1 min, 1 user, load average: 0.97, 0.25, 0.08 > Tasks: 145 total, 1 running, 144 sleeping, 0 stopped, 0 zombie > Cpu(s): 5.2%us, 3.0%sy, 1.2%ni, 86.8%id, 3.8%wa, 0.0%hi, 0.0%si, > 0.0%st > Mem: 8039608k total, 969380k used, 7070228k free, 1232k buffers > Swap: 16787768k total, 0k used, 16787768k free, 109448k cached > > Odd, remote netconsole did not capture the dmesg the E820 memory map. > > Jun 6 17:43:03 p34 [ 53.598611] ahci 0000:00:1f.2: AHCI 0001.0100 32 slots > 6 ports 3 Gbps 0x3f impl SATA mode Jun 6 17:43:03 p34 [ 53.598683] ahci > 0000:00:1f.2: flags: 64bit ncq led clo pio slum part Jun 6 17:43:03 p34 [ > 53.598986] scsi0 : ahci Jun 6 17:43:03 p34 [ 53.599131] scsi1 : ahci Jun > 6 17:43:03 p34 [ 53.599239] scsi2 : ahci Jun 6 17:43:03 p34 [ 53.599340] > scsi3 : ahci Jun 6 17:43:03 p34 [ 53.599438] scsi4 : ahci > > I will run with this patch for a while but so far, no issues, everything > looks great. > > Will it make it into 2.6.22-rc5? :) > > Justin. > - 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/