Re: [PATCH-for-9.1 v2 2/3] migration: Remove RDMA protocol handling

Hi Zhijian, On 29/3/24 02:53, Zhijian Li (Fujitsu) wrote: > > > On 28/03/2024 23:01, Peter Xu wrote: > > On Thu, Mar 28, 2024 at 11:18:04AM -0300, Fabiano Rosas wrote: > > > Philippe Mathieu-Daudé <philmd(a)linaro.org&gt; writes: > > > > > > > The whole RDMA subsystem was deprecated in commit e9a54265f5 > > > > ("hw/rdma: Deprecate the pvrdma device and the rdma subsystem") > > > > released in v8.2. > > > > > > > > Remove: > > > > - RDMA handling from migration > > > > - dependencies on libibumad, libibverbs and librdmacm > > > > > > > > Keep the RAM_SAVE_FLAG_HOOK definition since it might appears > > > > in old migration streams. > > > > > > > > Cc: Peter Xu <peterx(a)redhat.com&gt; > > > > Cc: Li Zhijian <lizhijian(a)fujitsu.com&gt; > > > > Acked-by: Fabiano Rosas <farosas(a)suse.de&gt; > > > > Signed-off-by: Philippe Mathieu-Daudé <philmd(a)linaro.org&gt; > > > > > > Just to be clear, because people raised the point in the last version, > > > the first link in the deprecation commit links to a thread comprising > > > entirely of rdma migration patches. I don't see any ambiguity on whether > > > the deprecation was intended to include migration. There's even an ack > > > from Juan. > > > > Yes I remember that's the plan. > > > > > > > > So on the basis of not reverting the previous maintainer's decision, my > > > Ack stands here. > > > > > > We also had pretty obvious bugs ([1], [2]) in the past that would have > > > been caught if we had any kind of testing for the feature, so I can't > > > even say this thing works currently. > > > > > > @Peter Xu, @Li Zhijian, what are your thoughts on this? > > > > Generally I definitely agree with such a removal sooner or later, as that's > > how deprecation works, and even after Juan's left I'm not aware of any > > other new RDMA users. Personally, I'd slightly prefer postponing it one > > more release which might help a bit of our downstream maintenance, however > > I assume that's not a blocker either, as I think we can also manage it. > > > > IMHO it's more important to know whether there are still users and whether > > they would still like to see it around. That's also one thing I notice that > > e9a54265f533f didn't yet get acks from RDMA users that we are aware, even > > if they're rare. According to [2] it could be that such user may only rely > > on the release versions of QEMU when it broke things. > > > > So I'm copying Yu too (while Zhijian is already in the loop), just in case > > someone would like to stand up and speak. > > > I admit RDMA migration was lack of testing(unit/CI test), which led to the a few > obvious bugs being noticed too late. > However I was a bit surprised when I saw the removal of the RDMA migration. I wasn't > aware that this feature has not been marked as deprecated(at least there is no > prompt to end-user). > > > > IMHO it's more important to know whether there are still users and whether > > they would still like to see it around. > > Agree. > I didn't immediately express my opinion in V1 because I'm also consulting our > customers for this feature in the future. > > Personally, I agree with Perter's idea that "I'd slightly prefer postponing it one > more release which might help a bit of our downstream maintenance" Do you mind posting a deprecation patch to clarify the situation?