From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from relay.sgi.com (relay3.corp.sgi.com [198.149.34.15]) by oss.sgi.com (Postfix) with ESMTP id 3883D7F4E for ; Mon, 16 Nov 2015 17:57:35 -0600 (CST) Received: from cuda.sgi.com (cuda1.sgi.com [192.48.157.11]) by relay3.corp.sgi.com (Postfix) with ESMTP id CE64AAC002 for ; Mon, 16 Nov 2015 15:57:31 -0800 (PST) Received: from mga14.intel.com ([192.55.52.115]) by cuda.sgi.com with ESMTP id GZ3OmQ5n0m76EggZ for ; Mon, 16 Nov 2015 15:57:30 -0800 (PST) Date: Mon, 16 Nov 2015 16:57:24 -0700 From: Ross Zwisler Subject: Re: [PATCH v2 03/11] pmem: enable REQ_FUA/REQ_FLUSH handling Message-ID: <20151116235724.GA10256@linux.intel.com> References: <1447459610-14259-1-git-send-email-ross.zwisler@linux.intel.com> <1447459610-14259-4-git-send-email-ross.zwisler@linux.intel.com> <22E0F870-C1FB-431E-BF6C-B395A09A2B0D@dilger.ca> <20151116133714.GB3443@quack.suse.cz> <20151116140526.GA6733@quack.suse.cz> <20151116194846.GB32203@linux.intel.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: List-Id: XFS Filesystem from SGI List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: xfs-bounces@oss.sgi.com Sender: xfs-bounces@oss.sgi.com To: Dan Williams Cc: Jan Kara , Dave Hansen , "J. Bruce Fields" , Linux MM , "H. Peter Anvin" , Jeff Layton , "linux-nvdimm@lists.01.org" , X86 ML , Ingo Molnar , Matthew Wilcox , Ross Zwisler , linux-ext4 , XFS Developers , Alexander Viro , Thomas Gleixner , Andreas Dilger , Theodore Ts'o , "linux-kernel@vger.kernel.org" , Jan Kara , linux-fsdevel , Andrew Morton , Matthew Wilcox On Mon, Nov 16, 2015 at 12:34:55PM -0800, Dan Williams wrote: > On Mon, Nov 16, 2015 at 11:48 AM, Ross Zwisler > wrote: > > On Mon, Nov 16, 2015 at 09:28:59AM -0800, Dan Williams wrote: > >> On Mon, Nov 16, 2015 at 6:05 AM, Jan Kara wrote: > >> > On Mon 16-11-15 14:37:14, Jan Kara wrote: > [..] > > Is there any reason why this wouldn't work or wouldn't be a good idea? > > We don't have numbers to support the claim that pcommit is so > expensive as to need be deferred, especially if the upper layers are > already taking the hit on doing the flushes. > > REQ_FLUSH, means flush your volatile write cache. Currently all I/O > through the driver never hits a volatile cache so there's no need to > tell the block layer that we have a volatile write cache, especially > when you have the core mm taking responsibility for doing cache > maintenance for dax-mmap ranges. > > We also don't have numbers on if/when wbinvd is a more performant solution. > > tl;dr Now that we have a baseline implementation can we please use > data to make future arch decisions? Sure, fair enough. _______________________________________________ xfs mailing list xfs@oss.sgi.com http://oss.sgi.com/mailman/listinfo/xfs