From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mike Snitzer Subject: Re: [PATCH 1/2] dmcache: flush superblock stats when retrieving status info Date: Fri, 10 May 2013 08:53:57 -0400 Message-ID: <20130510125357.GA7687@redhat.com> References: <20130508214845.GA7729@blackbox.djwong.org> <20130508220526.GA24132@redhat.com> <20130509203616.GA5713@blackbox.djwong.org> <20130509204437.GA5712@blackbox.djwong.org> <20130510101005.GE20880@debian> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <20130510101005.GE20880@debian> Sender: linux-kernel-owner@vger.kernel.org To: Joe Thornber Cc: "Darrick J. Wong" , device-mapper development , linux-kernel@vger.kernel.org List-Id: dm-devel.ids On Fri, May 10 2013 at 6:10am -0400, Joe Thornber wrote: > On Thu, May 09, 2013 at 01:44:38PM -0700, Darrick J. Wong wrote: > > When userspace queries dmcache for stats info, we should ensure that all the > > metadata gets flushed out of memory to disk. The current code neglects to > > update the disk copy of the hit/miss counters. > > Nack, I'm afraid. The commit is there purely to make sure the free > metadata blocks reported from the status are as high as possible. > [When a transaction is open we have to treat all blocks from the > previous transaction as allocated to allow rollback.] Right the commit is about presenting a more accurate status. Darrick's patch doesn't change what is reported for hit/miss counts (they are reported from in-core counters already, so accuracy isn't a concern). So I agree with what you're saying. Thanks Joe.