From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1765116AbdEAQnE (ORCPT ); Mon, 1 May 2017 12:43:04 -0400 Received: from mga06.intel.com ([134.134.136.31]:17537 "EHLO mga06.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1765051AbdEAQm7 (ORCPT ); Mon, 1 May 2017 12:42:59 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.37,401,1488873600"; d="scan'208";a="1142289688" From: "Verma, Vishal L" To: "Williams, Dan J" , "toshi.kani@hpe.com" CC: "linux-kernel@vger.kernel.org" , "linux-nvdimm@lists.01.org" , "Jiang, Dave" Subject: Re: [PATCH] libnvdimm: rework region badblocks clearing Thread-Topic: [PATCH] libnvdimm: rework region badblocks clearing Thread-Index: AQHSwa+YcVsS+Z63R0W+DwYQOiEVzKHgEtUAgAACnICAAAJfAIAABYyAgAABS4CAAADsgIAABR2AgAABNIA= Date: Mon, 1 May 2017 16:42:51 +0000 Message-ID: <1493656965.4424.0.camel@intel.com> References: <149355594185.9917.1577772489949690281.stgit@dwillia2-desk3.amr.corp.intel.com> <1493652871.30303.15.camel@hpe.com> <1493655131.30303.17.camel@hpe.com> <1493655607.30303.19.camel@hpe.com> In-Reply-To: Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [10.254.177.87] Content-Type: text/plain; charset="utf-8" Content-ID: <76B174B9D19ABE4FB9B96FD1F9CEB868@intel.com> MIME-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: 8bit X-MIME-Autoconverted: from base64 to 8bit by mail.home.local id v41GiR5F005954 On Mon, 2017-05-01 at 09:38 -0700, Dan Williams wrote: > On Mon, May 1, 2017 at 9:20 AM, Kani, Toshimitsu > wrote: > > On Mon, 2017-05-01 at 09:16 -0700, Dan Williams wrote: > > > On Mon, May 1, 2017 at 9:12 AM, Kani, Toshimitsu > > com> > > > wrote: > > > > On Mon, 2017-05-01 at 08:52 -0700, Dan Williams wrote: > > > > > On Mon, May 1, 2017 at 8:43 AM, Dan Williams > > > > inte > > > > > l.co > > > > > m> wrote: > > > > > > On Mon, May 1, 2017 at 8:34 AM, Kani, Toshimitsu > > > > > i@hp > > > > > > e.co > > > > > > m> wrote: > > > > > > > On Sun, 2017-04-30 at 05:39 -0700, Dan Williams wrote: > > > > > > > >  : > > > > > > > > > > > > > > Hi Dan, > > > > > > > > > > > > > > I was testing the change with CONFIG_DEBUG_ATOMIC_SLEEP > > > > > > > set > > > > > > > this time, and hit the following BUG with BTT.  This is a > > > > > > > separate issue (not introduced by this patch), but it > > > > > > > shows > > > > > > > that we have an issue with the DSM call path as well. > > > > > > > > > > > > Ah, great find, thanks! We don't see this in the unit tests > > > > > > because the nfit_test infrastructure takes no sleeping > > > > > > actions > > > > > > in its simulated DSM path. Outside of converting btt to use > > > > > > sleeping locks I'm not sure I see a path forward. I wonder > > > > > > how > > > > > > bad the performance impact of that would be? Perhaps with > > > > > > opportunistic spinning it won't be so bad, but I don't see > > > > > > another choice. > > > > > > > > > > It's worse than that. Part of the performance optimization of > > > > > BTT > > > > > I/O was to avoid locking altogether when we could rely on a > > > > > BTT > > > > > lane percpu, so that would also need to be removed. > > > > > > > > I do not have a good idea either, but I'd rather disable this > > > > clearing in the regular BTT write path than adding sleeping > > > > locks > > > > to BTT. Clearing a bad block in the BTT write path is > > > > difficult/challenging since it allocates a new block. > > > > > > Actually, that may make things easier. Can we teach BTT to track > > > error blocks and clear them before they are reassigned? > > > > I was thinking the same after sending it.  I think we should be > > able to > > do that. > > Ok, but we obviously can't develop something that detailed while the > merge window is open, so I think that means we need to revert commit > e88da7998d7d "Revert 'libnvdimm: band aid btt vs clear poison > locking'" and leave BTT I/O-error-clearing disabled for this cycle > and > try again for 4.13. Agreed, I'll work on something to track badblocks and clear them outside the IO path.