This is driving people away exactly because they don't know this is what's asked of them, and why they are asked of this AMP requirement in the first place. To someone who's already familiar with the context, this is little to be worried about. It's now the process that requires everyone to become familiarized with the AMP requirement that becomes costly. More importantly, this is not a question of whether it's too much, but whether it should be there in the first place. If it's merely a question of cost I imagine you'd have no trouble stepping up and support all of the future operators for AMP :)
-sz On 2019/05/28 23:49:52, Marco de Abreu <[email protected]> wrote: > I'm having trouble in how far adding the name of an operator in a single > file is too much to expect from somebody and how this is driving people > away. > > If somebody adds a tutorial, they also have to add the tutorial to a > specific file. As far as I can tell, this has not resulted in people not > wanting to write tutorials anymore or it being considered as such a big > burden. > > So far, I'm really not following why adding a single line to a single file > is considered such a big deal. Considering how long this guide [1] already > is, what's the harm in adding this as an additional instruction? (AMP is > not mentioned there yet, it would be great if that could be follow up) > > [1] > https://mxnet.incubator.apache.org/versions/master/faq/add_op_in_backend.html > > -Marco > > On Wed, May 29, 2019 at 1:42 AM Sheng Zha <[email protected]> wrote: > > > AMP is in contrib so there's no guarantee that the API is final. Adopting > > the test as-is is harmful because operator authors should not be required > > to invest in an experimental feature that they are not aware of. > > > > I'm all for openness and welcoming, but think about whether you'd like to > > turn away developers who just want to write a CPU-only operator. The more > > you impose on the developers the less likely they will make the > > contribution through. > > > > Having an unfamiliar operator in AMP as a warning could let everyone know > > what the support state is whenever that feature is used. For those who care > > about this, they would see the warning and add the support to get the speed > > benefit of not casting to fp32. In this case, rather than imposing it to > > developers who don't know about AMP, the one who actually uses AMP and > > cares about this feature would drive the work forward. > > > > -sz > > > > On 2019/05/28 23:25:43, Marco de Abreu <[email protected]> wrote: > > > While AMP might be an experimental feature, I rather would like to put > > the > > > focus on the maturity of its interfaces. If the interfaces and the > > actions > > > developers have to do aren't finalized yet, I'd agree with disabling the > > > test. But if the API is final and easy to use, I don't see why adopting > > > early on would be harmful. But from what I can see, the output of the > > test > > > is very meaningful and explicit, easily understandable and offers the > > > developer a clear list of action items that they can follow. > > > > > > If people actually start commenting "CI test failure seems unrelated to > > my > > > change, please proceed and merge", we should advise them to please open > > the > > > result tab, which will directly show the clear list of action items. > > > Committers should support these contributors who are not that familiar > > with > > > our CI system and explain to them how they can retrieve the reasons for > > the > > > failure. Simply ignoring the fact that the change is not compatible with > > > AMP doesn't seem to be the right way. > > > > > > I think nobody is opposed to having AMP in MXNet. As part of accepting > > the > > > feature, we also added AMP to the established methods including the > > coding > > > constraints and other checks that come with it. Lets be open and welcome > > to > > > this new feature and come back if the turnaround time is actually too > > high. > > > > > > -Marco > > > > > > > > > On Wed, May 29, 2019 at 1:13 AM Sheng Zha <[email protected]> wrote: > > > > > > > The support for AMP should not be a burden of authors of new operators. > > > > The lint analogy doesn't apply because lint is for established and > > accepted > > > > coding standard at MXNet and AMP is not. AMP is an experimental feature > > > > right now and it doesn't make sense to require contributors to invest > > in > > > > it. Keeping this as error will inevitably cause comments like "CI test > > > > failure seems unrelated to my change, please proceed and merge". > > > > > > > > -sz > > > > > > > > On 2019/05/28 22:51:30, Marco de Abreu <[email protected]> > > wrote: > > > > > Hi, > > > > > > > > > > I'm generally in favour of these kind of tests since they make > > developers > > > > > aware of changes they have to make which they would usually not be > > aware > > > > > of. We have a similar test for tutorials, for example. Whenever > > somebody > > > > > adds a tutorial, there's a validation that assures that all > > contraints in > > > > > our testing environment are met and that they are properly tied into > > the > > > > > system. This AMP test fits into the same category in my opinion and > > we > > > > > never heard bad feedback about these kind of checks. > > > > > > > > > > What seems to be bothering people is the fact that the feedback time > > is > > > > too > > > > > high. Thus, I'd like to propose to move the test into the sanity-test > > > > stage > > > > > instead of doing it as part of the unit tests which take quite a bit > > of > > > > > time until they're actually executed. The sanity checks run > > immediately > > > > and > > > > > give a response within about 1 minute. > > > > > > > > > > While I understand that this might increase the amount of work a > > > > developer > > > > > has to do if they develop a new operator, I think that this is the > > right > > > > > thing to do. Developers won't know of every single feature other > > people > > > > > worked on and thus might simply miss adding the support for it. This > > kind > > > > > of test on the other hand makes them aware of it. If they'd like to > > opt > > > > > out, it's one single line they would have to change and then they're > > > > > totally fine. On the other hand, this might motivate them to add the > > > > > support since the kernel would be the last piece and everything else > > > > would > > > > > already be implemented. > > > > > > > > > > Considering how often a PR gets declined because of linting errors, > > I'd > > > > say > > > > > that these kind of errors are WAY more frequent that AMP telling > > somebody > > > > > to add their operator to a list. Considering that this would only > > have to > > > > > be done once per operator, that's work of about one minute. Add that > > to > > > > the > > > > > waiting time of the sanity check and you're left with about five > > "wasted" > > > > > minutes. > > > > > > > > > > I'm opposed towards adding a warning or treating them as float32 by > > > > default > > > > > since the operator author wouldn't notice. What will happen is that > > > > people > > > > > won't know about AMP and simply forget about low precision in general > > > > until > > > > > they're actively reminded. This check will remind them actively and > > thus > > > > > bring more attention to the feature. I know that the feature is still > > > > > experimental, but we have just started with the 1.6 branch and thus > > > > there's > > > > > enough time to make the experimental features production ready. > > Adding > > > > this > > > > > test early on will allow others to add the support for AMP during the > > > > early > > > > > stage of the 1.6 branch instead of asking them in the last few weeks > > > > before > > > > > a release. The result would only be that stuff is rushed or > > forgotten. > > > > > > > > > > To sum it up: I think this test is good and it should be kept as > > error, > > > > but > > > > > it should be moved to sanity checks. > > > > > > > > > > -Marco > > > > > > > > > > On Wed, May 29, 2019 at 12:21 AM Sheng Zha <[email protected]> > > wrote: > > > > > > > > > > > Thanks for initiating the discussion. > > > > > > > > > > > > The premise for adding the test was to make sure that AMP feature > > is > > > > "not > > > > > > broken", but that's IMO not the right view. AMP is not supposed to > > > > support > > > > > > a new operator it hasn't seen before in the first place. There's no > > > > way for > > > > > > it to know whether the fp32 cast should happen or not. So AMP > > feature > > > > > > cannot provide the guarantee that it works for all future > > operators. > > > > Thus, > > > > > > adding new operators to AMP list should be considered new feature > > > > instead > > > > > > of fixing existing feature. > > > > > > > > > > > > The AMP test that breaks upon the addition of new operator is thus > > > > > > equivalent to forcing developers of the new operator to add the new > > > > support > > > > > > for AMP. This feels wrong. Especially given that AMP is an > > experimental > > > > > > feature in contrib namespace (i.e. no semver guarantee), this > > practice > > > > > > should be stopped immediately. We cannot force new developers to > > invest > > > > > > into experimental feature this way. > > > > > > > > > > > > I'd suggest the following changes: > > > > > > - for new operators that aren't registered in AMP, cast to float32 > > by > > > > > > default and print one-time warning. People using AMP who want to > > avoid > > > > > > casting can register it in the AMP's list. > > > > > > - change the test to print warning about the operators that are not > > > > listed > > > > > > so that it's easy to track the problem. > > > > > > > > > > > > -sz > > > > > > > > > > > > On 2019/05/28 21:32:42, Przemys��aw Tr��dak <[email protected]> > > > > wrote: > > > > > > > Dear Community, > > > > > > > > > > > > > > One of the recently merged features of the 1.5 release, AMP > > > > (Automatic > > > > > > Mixed Precision) support (PR [1], design doc [5]), introduced a > > > > requirement > > > > > > that every new operator added to MXNet would need to be present in > > 1 > > > > of the > > > > > > lists (in [2]). To make sure that this requirement is not broken > > when > > > > > > somebody adds a new operator and does not know about AMP's > > existence, a > > > > > > test was added to CI ([3]). > > > > > > > > > > > > > > A few people reached out to me (the original author of the > > feature) > > > > > > saying this test increases a burden on a developer of new > > operators and > > > > > > should not be an actual error, but just warning (PR for that change > > > > [4]). > > > > > > That is why I would like to present a motivation for it and discuss > > > > with > > > > > > the wider audience why I feel it was necessary. > > > > > > > > > > > > > > First, for people who do not know the details of what AMP is - > > it is > > > > a > > > > > > solution that tries to automatically apply best practices of > > training > > > > in > > > > > > lower precision (FP16) to user's FP32 model in order to fully > > utilize > > > > > > capabilities of modern GPUs (and potentially other hardware in the > > > > future). > > > > > > It does so by casting to lower precision inputs to operators > > > > benefitting > > > > > > from it, while casting to full precision inputs of operators that > > are > > > > > > unsafe to run in lower precision or just do not support it. > > > > > > > > > > > > > > The first iteration of AMP kept 2 main lists of operators - > > operators > > > > > > that are beneficial and safe to do in fp16 and operators that need > > to > > > > be > > > > > > cast to FP32. The problem (raised in review of the PR [6], [8]) is > > how > > > > to > > > > > > make sure that the feature works as intended and is not > > inadvertently > > > > > > broken by somebody adding a new operator. The failure scenario > > here is > > > > > > adding a new operator that does not support FP16 and so should be > > cast > > > > to > > > > > > FP32, but AMP does not know about its existence and so does not do > > the > > > > > > casting. The solution proposed in the review was to implicitly > > treat > > > > all of > > > > > > the unknown operators as FP32-only and keep the list of operators > > that > > > > work > > > > > > fine in both FP16 and FP32. This solution however does not really > > work, > > > > > > because there are multiple operators (most notably optimizers) > > where > > > > > > introducing additional casting of the input to FP32 would break the > > > > > > operator. > > > > > > > > > > > > > > That is why after discussion with a few members of the > > community, I > > > > > > decided to proceed with all lists being explicit and introducing > > the > > > > test > > > > > > that would fail when somebody added an operator without > > classifying it > > > > into > > > > > > 1 of the categories, and explain clearly how to do it [7]. It is > > not > > > > ideal > > > > > > solution, as it introduces some burden on the developers who are > > not > > > > aware > > > > > > about AMP, however in the typical case of adding at most a few > > > > operators to > > > > > > MXNet the inconvenience is I think pretty minor while important > > for the > > > > > > feature correctness going forward. > > > > > > > > > > > > > > I would like to gather Community feedback and ideas how to handle > > > > this > > > > > > situation. > > > > > > > > > > > > > > [1] https://github.com/apache/incubator-mxnet/pull/14173 > > > > > > > [2] > > > > > > > > > > > > https://github.com/apache/incubator-mxnet/blob/master/python/mxnet/contrib/amp/lists/symbol.py > > > > > > > [3] > > > > > > > > > > > > https://github.com/apache/incubator-mxnet/blob/master/tests/python/unittest/test_amp.py > > > > > > > [4] https://github.com/apache/incubator-mxnet/pull/15085 > > > > > > > [5] > > > > > > > > > > > > https://docs.google.com/document/d/1sQzMoPEwux0WXSWirY07us1POD_6Y8pLYq--b9Fvd1o/edit?usp=sharing > > > > > > > [6] > > > > > > > > > > > > https://github.com/apache/incubator-mxnet/pull/14173#discussion_r270728019 > > > > > > > [7] > > > > > > > > > > > > https://github.com/apache/incubator-mxnet/blob/master/tests/python/unittest/test_amp.py#L62-L80 > > > > > > > [8] > > > > > > > > > > > > https://github.com/apache/incubator-mxnet/pull/14173#pullrequestreview-235846341 > > > > > > > > > > > > > > > > > > > > > > > > > > > >
