Messages in this thread | | | Subject | Re: [PATCH v2 0/7] Lazily allocate memslot rmaps | From | Paolo Bonzini <> | Date | Tue, 4 May 2021 09:21:48 +0200 |
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On 03/05/21 19:31, Ben Gardon wrote: > On Mon, May 3, 2021 at 6:45 AM Paolo Bonzini <pbonzini@redhat.com> wrote: >> >> On 29/04/21 23:18, Ben Gardon wrote: >>> This series enables KVM to save memory when using the TDP MMU by waiting >>> to allocate memslot rmaps until they are needed. To do this, KVM tracks >>> whether or not a shadow root has been allocated. In order to get away >>> with not allocating the rmaps, KVM must also be sure to skip operations >>> which iterate over the rmaps. If the TDP MMU is in use and we have not >>> allocated a shadow root, these operations would essentially be op-ops >>> anyway. Skipping the rmap operations has a secondary benefit of avoiding >>> acquiring the MMU lock in write mode in many cases, substantially >>> reducing MMU lock contention. >>> >>> This series was tested on an Intel Skylake machine. With the TDP MMU off >>> and on, this introduced no new failures on kvm-unit-tests or KVM selftests. >> >> Thanks, I only reported some technicalities in the ordering of loads >> (which matter since the loads happen with SRCU protection only). Apart >> from this, this looks fine! > > Awesome to hear, thank you for the reviews. Should I send a v3 > addressing those comments, or did you already make those changes when > applying to your tree?
No, I didn't (I wanted some oversight, and this is 5.14 stuff anyway).
Paolo
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