From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dave Wysochanski Subject: RE: patch to discovery.c to still get pathpriorityforpaths with path state of PATH_DOWN Date: Wed, 15 Nov 2006 15:28:35 -0500 Message-ID: <1163622515.5844.4.camel@linux-cxyg.rtp.netapp.com> References: <6CCEAEDF4D06984A83F427424F47D6E4013D1552@CORPUSMX40A.corp.emc.com> Reply-To: device-mapper development Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <6CCEAEDF4D06984A83F427424F47D6E4013D1552@CORPUSMX40A.corp.emc.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: dm-devel-bounces@redhat.com Errors-To: dm-devel-bounces@redhat.com To: Edward Goggin Cc: dm-devel@redhat.com, christophe.varoqui@free.fr List-Id: dm-devel.ids On Wed, 2006-11-15 at 14:48 -0500, Edward Goggin wrote: > On Wednesday, November 15, 2006 1:49 AM, Dave Wysochanski wrote > > > One other thought I had was the notion of a "priority valid" > > flag (or a > > special priority value) in the path for the case of > > group_by_prio. Set > > it to invalid in alloc_path(), then just don't add the path to the > > multipath struct in coalesce_paths() if the priority value > > was invalid. > > Then over in checkerloop(), add the path to the multipath map when you > > get a valid priority. > > > > It is more complicated than that I'm sure (e.g. checkerloop() assumes > > pp->mpp is non-null in places, etc) but seemed like a half-decent > > approach to at least consider. > > > > This approach doesn't take into consideration the general case of a > > change in path priority though. > > I very much like the first part of your "priority valid" idea > mentioned above. > > I've enclosed a patch for the first part of your idea. The patch > should address the concern you had about recalculating priority > for a path when its path state changes from not PATH_DOWN to > PATH_DOWN. It now only retrieves the priority for PATH_DOWN > paths if the path's priority has never been successfully > retrieved before. > Great. Your patch looks fine. > I've punted for now on the reloading of the map if a path priority > change has caused a path group membership change. This is kind of > complex, has lots of down sides, and there doesn't seem to be a > need for it as of now. Sure that's fine. That would be extreme and I'm all for simplicity.