From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christoph Hellwig Date: Tue, 14 Jun 2016 18:24:23 +0000 Subject: Re: [RFC PATCH-tip 6/6] xfs: Enable reader optimistic spinning for DAX inodes Message-Id: <20160614182423.GA6330@infradead.org> List-Id: References: <1465927959-39719-1-git-send-email-Waiman.Long@hpe.com> <1465927959-39719-7-git-send-email-Waiman.Long@hpe.com> In-Reply-To: <1465927959-39719-7-git-send-email-Waiman.Long@hpe.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Waiman Long Cc: Peter Zijlstra , Ingo Molnar , linux-kernel@vger.kernel.org, x86@kernel.org, linux-alpha@vger.kernel.org, linux-ia64@vger.kernel.org, linux-s390@vger.kernel.org, linux-arch@vger.kernel.org, xfs@oss.sgi.com, Davidlohr Bueso , Jason Low , Dave Chinner , Scott J Norton , Douglas Hatch On Tue, Jun 14, 2016 at 02:12:39PM -0400, Waiman Long wrote: > This patch enables reader optimistic spinning for inodes that are > under a DAX-based mount point. > > On a 4-socket Haswell machine running on a 4.7-rc1 tip-based kernel, > the fio test with multithreaded randrw and randwrite tests on the > same file on a XFS partition on top of a NVDIMM with DAX were run, > the aggregated bandwidths before and after the patch were as follows: And why is this specific to DAX? Many I/O operations already never got out to disk, and ilock is mostly held for operations that have nothing to do with disk I/O.