Hi Gleb, On 05/23/2014 05:43 PM, Gleb Natapov wrote: > CCing Paolo. > > On Tue, May 20, 2014 at 01:45:55PM +0800, Gu Zheng wrote: >> Hi Gleb, >> Excuse me for offline noisy. > You will get much quicker response if you'll post to the list :) Got it.:) > >> There was a patch(from Chen Fan, last august) about releasing vcpu when >> closing vcpu fd <http://www.spinics.net/lists/kvm/msg95701.html>, but >> your comment said "Attempt where made to make it possible to destroy >> individual vcpus separately from destroying VM before, but they were >> unsuccessful thus far." >> So what is the pain here? If we want to achieve the goal, what should we do? >> Looking forward to your further comments.:) >> > CPU array is accessed locklessly in a lot of places, so it will have to be RCUified. > There was attempt to do so 2 year or so ago, but it didn't go anyware. Adding locks is > to big a price to pay for ability to free a little bit of memory by destroying vcpu. Yes, it's a pain here. But if we want to implement "vcpu hot-remove", this must be fixed sooner or later. And any guys working on kvm "vcpu hot-remove" now? > An > alternative may be to make sure that stopped vcpu takes as little memory as possible. Yeah. But if we add a new vcpu with the old id that we stopped before, it will fail. Best regards, Gu > > -- > Gleb. > -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
