On Wed, 30 May 2018 13:05:46 -0600 Jens Axboe <axboe@xxxxxxxxx> wrote: > On 5/29/18 5:27 PM, Mike Snitzer wrote: > > On Tue, May 29 2018 at 4:09am -0400, > > Christoph Hellwig <hch@xxxxxx> wrote: > > > >> On Tue, May 29, 2018 at 09:22:40AM +0200, Johannes Thumshirn > >> wrote: > >>> For a "Plan B" we can still use the global knob that's already in > >>> place (even if this reminds me so much about scsi-mq which at > >>> least we haven't turned on in fear of performance regressions). > >>> > >>> Let's drop the discussion here, I don't think it leads to > >>> something else than flamewars. > >> > >> If our plan A doesn't work we can go back to these patches. For > >> now I'd rather have everyone spend their time on making Plan A > >> work then preparing for contingencies. Nothing prevents anyone > >> from using these patches already out there if they really want to, > >> but I'd recommend people are very careful about doing so as you'll > >> lock yourself into a long-term maintainance burden. > > > > Restating (for others): this patchset really isn't about > > contingencies. It is about choice. > > > > Since we're at an impasse, in the hopes of soliciting definitive > > feedback from Jens and Linus, I'm going to attempt to reset the > > discussion for their entry. > > > > In summary, we have a classic example of a maintainer stalemate > > here: 1) Christoph, as NVMe co-maintainer, doesn't want to allow > > native NVMe multipath to actively coexist with dm-multipath's NVMe > > support on the same host. > > 2) I, as DM maintainer, would like to offer this flexibility to > > users -- by giving them opt-in choice to continue using existing > > dm-multipath with NVMe. (also, both Red Hat and SUSE would like to > > offer this). > > > > There is no technical reason why they cannot coexist. Hence this > > simple patchset that was originally offered by Johannes Thumshirn > > with contributions from myself. > > Here's what I think - flag days tend to suck. They may be more > convenient for developers, but they inflict pain on users. Sometimes > they prevent them from moving forward, since updates are now gated on > external dependencies. Moving forward with a new architecture is > great, but proper care has to be given to existing users of > multipath, regardless of how few they may be. > > This patchset seems pretty clean and minimalist. Realistically, I'm > guessing that SUSE and RH will ship it regardless of upstream status. > Without it we're having a choice of disappointing (paying) customers or disappointing the upstream community. Guess. Cheers, Hannes -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
