From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S941252AbdDTEwn (ORCPT ); Thu, 20 Apr 2017 00:52:43 -0400 Received: from mail-ua0-f175.google.com ([209.85.217.175]:34372 "EHLO mail-ua0-f175.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S941246AbdDTEwi (ORCPT ); Thu, 20 Apr 2017 00:52:38 -0400 MIME-Version: 1.0 In-Reply-To: References: <20170420030959.GC23085@kernel.dk> From: Andy Lutomirski Date: Wed, 19 Apr 2017 21:52:17 -0700 Message-ID: Subject: Re: [PATCH 0/5] nvme APST fixes/improvements for 4.11 To: Andy Lutomirski Cc: Jens Axboe , "linux-kernel@vger.kernel.org" , Kai-Heng Feng , linux-nvme , Christoph Hellwig , Sagi Grimberg , Keith Busch Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Apr 19, 2017 at 8:55 PM, Andy Lutomirski wrote: > On Wed, Apr 19, 2017 at 8:10 PM, Jens Axboe wrote: >> On Wed, Apr 19 2017, Andy Lutomirski wrote: >>> Sorry for waiting so long for this. I was waiting for feedback from >>> Samsung, but they haven't root-caused the issue yet, and I should >>> have just done this from the beginning. >>> >>> This series makes APST more debuggable and updates the quirk list. >>> The quirks I'm aware of are: >>> >>> - Samsung 950 series SSDs in Dell XPS 15 9550 and Precision 5510 >>> laptops (which are essentially the same laptop) can lose their >>> PCIe link if they're allowed to use the deepest APST state. >>> Samsung engineers have an affected system and are working on >>> it. The same exact SSDs in other machines (even an XPS 13) >>> seem to work fine. >>> >>> - One Toshiba device malfunctions if APST is used at all. >> >> You need to split this series in two, patches 1-3 can wait. For 4.11, >> all we need to do is turn off APST on any device that potentially has >> this problem. >> >>> One thing that improves my confidence that there aren't too many >>> more problems with APST is that Ubuntu has backported APST to Zesty, >>> so it's already gotten a bit of testing in a widely used (if very >>> new) release. >> >> Honestly, I think the best path for 4.11 is to turn off APST by default, >> make it opt-in instead. I don't share your optimism here, as I made >> clear back from before we even merged this feature. >> >> > > I can make it so that force_apst=0 means no APST and force_apst=1 mean > yes APST and we could try again with a quirk list for 4.12. There's a > decent chance that a few more weeks with Ubuntu having APST on will > shake out all the problems fairly quickly. Here's a more concrete and more sensible proposal: For 4.11: force_apst=0: Default. APST off on all Samsung 950-like devices regardless of what laptop and on the Toshiba device. force_apst=1: Use APST except where known bad. APST deepest state disabled on Samsung 950-like devices on XPS 15 and Precision 5510. APST off on the Toshiba device. force_apst=2: APST fully on regardless of any quirks. For 4.12-rc1: force_apst=0 works like force_apst=1, but we keep both values for compatibility and in case we need to add another overly broad quirk some day. Would something like this make sense?