Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758847Ab3EGTFF (ORCPT ); Tue, 7 May 2013 15:05:05 -0400 Received: from mail-qe0-f54.google.com ([209.85.128.54]:64227 "EHLO mail-qe0-f54.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753721Ab3EGTFB (ORCPT ); Tue, 7 May 2013 15:05:01 -0400 MIME-Version: 1.0 In-Reply-To: <384171828.66802.1367942365492.JavaMail.mail@webmail05> References: <337833384.57445.1361860509194.JavaMail.mail@webmail08> <569718148.80620.1361906088301.JavaMail.mail@webmail13> <771333906.75854.1367057440028.JavaMail.mail@webmail08> <518097B8.4020402@gmail.com> <384171828.66802.1367942365492.JavaMail.mail@webmail05> Date: Tue, 7 May 2013 13:05:00 -0600 Message-ID: Subject: Re: Abysmal HDD/USB write speed after sleep on a UEFI system From: Robert Hancock To: "Artem S. Tashkinov" Cc: Bjorn Helgaas , Alan Stern , Linus Torvalds , linux-kernel , linux-pci@vger.kernel.org, "Rafael J. Wysocki" , psusi@ubuntu.com Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2620 Lines: 56 On Tue, May 7, 2013 at 9:59 AM, Artem S. Tashkinov wrote: > May 7, 2013 09:25:40 PM, Bjorn Helgaas wrote: >> [+cc Phillip] >> >>> I would suspect that Windows' complaint about the BIOS mucking up the MTRRs >>> is likely the best hint. Likely Windows is detecting the problem and fixing >>> it up on resume, thus it only complains about "reduced resume performance". >>> If the MTRRs are messed up, then quite likely parts of RAM have become >>> uncacheable, causing performance to get randomly slaughtered in various >>> ways. >>> >>> From looking at the code it's not clear if we are checking/restoring the >>> MTRR contents after resume. If not, maybe we should be. >> >>I agree; the MTRR warning is a good hint. Artem? >> >>Phillip, I cc'd you because you have similar hardware and your >>https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1131468 report is >>slightly similar. Have you seen anything like this "reduced >>performance after resume" issue? If so, can you collect /proc/mtrr >>contents before and after suspending? >> > > Like Robert Hancock correctly noted the Linux kernel lacks the code to check > for MTTR changes after resume - I'm not a kernel hacker to write such a code ;-) > > Likewise there's no code to see if RAM pages have become uncacheable - i.e > I've no idea how to check it either. > > According to /proc/mttr nothing changes on resume - only Windows detects > the discrepancy between MTTR regions on resume. dmesg contains no warnings > or errors (aside from usual ACPI SATA warnings - but they happen right on > boot - so I highly doubt the ACPI or SATA layers can be the culprit, since USB > exhibits a similar performance degradation). I'm not sure if reading /proc/mtrr actually reads the registers out of the CPU each time, or whether we just return the cached values we read out during initial boot-up. If the latter, then this output isn't really useful as there's no guarantee the values are still intact. > > In short, there's little to nothing that I can check. > > That bug report has nothing to do with my problem - my PC suspends and > resumes more or less correctly - everything works (albeit some parts don't > work as they should). That person also has a very outdated BIOS - 1904 from > 08/15/2011. I wouldn't be surprised if BIOS update solved his problem. > > Best regards, > > Artem -- 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/