From mboxrd@z Thu Jan 1 00:00:00 1970 From: keith.busch@intel.com (Keith Busch) Date: Wed, 4 Apr 2018 08:30:27 -0600 Subject: [PATCH] nvme-multipath: implement active-active round-robin path selector In-Reply-To: References: <20180327043851.6640-1-baegjae@gmail.com> <20180328080646.GB20373@lst.de> <20180328194741.GJ13039@localhost.localdomain> <20180330070651.GA17095@lst.de> Message-ID: <20180404143027.GE4485@localhost.localdomain> On Fri, Mar 30, 2018@09:04:46AM +0000, Eric H. Chang wrote: > We internally call PCIe-retimer as HBA. It's not a real Host Bus Adapter that translates the interface from PCIe to SATA or SAS. Sorry for the confusion. Please don't call a PCIe retimer an "HBA"! :) While your experiment is setup to benefit from round-robin, my only concern is it has odd performance in a real world scenario with IO threads executing in different nodes. Christoph's proposal will naturally utilize both paths optimally there, where round-robin will saturate node interlinks. Not that I'm against having the choice; your setup probably does represent real use. But if we're going to have multiple choice, user documentation on nvme path selectors will be useful here.