Jay Pipes <jaypi...@gmail.com> 于2018年9月29日周六 上午5:51写道：
> On 09/28/2018 04:42 PM, Eric Fried wrote: > > On 09/28/2018 09:41 AM, Balázs Gibizer wrote: > >> On Fri, Sep 28, 2018 at 3:25 PM, Eric Fried <openst...@fried.cc> wrote: > >>> It's time somebody said this. > >>> > >>> Every time we turn a corner or look under a rug, we find another use > >>> case for provider traits in placement. But every time we have to have > >>> the argument about whether that use case satisfies the original > >>> "intended purpose" of traits. > >>> > >>> That's only reason I've ever been able to glean: that it (whatever "it" > >>> is) wasn't what the architects had in mind when they came up with the > >>> idea of traits. We're not even talking about anything that would > require > >>> changes to the placement API. Just, "Oh, that's not a *capability* - > >>> shut it down." > >>> > >>> Bubble wrap was originally intended as a textured wallpaper and a > >>> greenhouse insulator. Can we accept the fact that traits have (many, > >>> many) uses beyond marking capabilities, and quit with the arbitrary > >>> restrictions? > >> > >> How far are we willing to go? Does an arbitrary (key: value) pair > >> encoded in a trait name like key_`str(value)` (e.g. CURRENT_TEMPERATURE: > >> 85 encoded as CUSTOM_TEMPERATURE_85) something we would be OK to see in > >> placement? > > > > Great question. Perhaps TEMPERATURE_DANGEROUSLY_HIGH is okay, but > > TEMPERATURE_<specific_number> is not. > > That's correct, because you're encoding >1 piece of information into the > single string (the fact that it's a temperature *and* the value of that > temperature are the two pieces of information encoded into the single > string). > > Now that there's multiple pieces of information encoded in the string > the reader of the trait string needs to know how to decode those bits of > information, which is exactly what we're trying to avoid doing (because > we can see from the ComputeCapabilitiesFilter, the extra_specs mess, and > the giant hairball that is the NUMA and CPU pinning "metadata requests" > how that turns out). > May I understand the one of Jay's complain is about metadata API undiscoverable? That is extra_spec mess and ComputeCapabilitiesFilter mess? Another complain is about the information in the string. Agree with that TEMPERATURE_<specific_number> is terriable. I prefer the way I used in nvdimm proposal now, I don't want to use Trait NVDIMM_DEVICE_500GB, NVDIMM_DEVICE_1024GB. I want to put them into the different resource provider, and use min_size, max_size limit the allocation. And the user will request with resource class like RC_NVDIMM_GB=512. > > > This thread isn't about setting these parameters; it's about getting > > us to a point where we can discuss a question just like this one > > without running up against: > > > "That's a hard no, because you shouldn't encode key/value pairs in > traits." > > > > "Oh, why's that?" > > > > "Because that's not what we intended when we created traits." > > > > "But it would work, and the alternatives are way harder." > > > > "-1" > > > > "But..." > > > > "-I > > I believe I've articulated a number of times why traits should remain > unary pieces of information, and not just said "because that's what we > intended when we created traits". > > I'm tough on this because I've seen the garbage code and unmaintainable > mess that not having structurally sound data modeling concepts and > information interpretation rules leads to in Nova and I don't want to > encourage any more of it. > > -jay > > > __________________________________________________________________________ > OpenStack Development Mailing List (not for usage questions) > Unsubscribe: openstack-dev-requ...@lists.openstack.org?subject:unsubscribe > http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev >
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