| Message ID | 20221201195718.1409782-1-vipinsh@google.com (mailing list archive) |
|---|---|
| Headers | show |
| Series | NUMA aware page table allocation | expand |
On Thu, Dec 01, 2022 at 11:57:16AM -0800, Vipin Sharma wrote: > Hi, > > This series improves page table accesses by allocating page tables on > the same NUMA node where underlying physical page is present. > > Currently page tables are allocated during page faults and page splits. > In both instances page table location will depend on the current thread > mempolicy. This can create suboptimal placement of page tables on NUMA > node, for example, thread doing eager page split is on different NUMA > node compared to page it is splitting. > > Reviewers please provide suggestion to the following: > > 1. Module parameter is true by default, which means this feature will > be enabled by default. Is this okay or should I set it to false? > > 2. I haven't reduced KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE considering that > it might not be too much of an impact as only online nodes are filled > during topup phase and in many cases some of these nodes will never > be refilled again. Please let me know if you want this to be > reduced. > > 3. I have tried to keep everything in x86/mmu except for some changes in > virt/kvm/kvm_main.c. I used __weak function so that only x86/mmu will > see the change, other arch nothing will change. I hope this is the > right approach. > > 4. I am not sure what is the right way to split patch 2. If you think > this is too big for a patch please let me know what would you prefer. I agree it's too big. The split_shadow_page_cache changes can easily be split into a separate commit.
Hi, This series improves page table accesses by allocating page tables on the same NUMA node where underlying physical page is present. Currently page tables are allocated during page faults and page splits. In both instances page table location will depend on the current thread mempolicy. This can create suboptimal placement of page tables on NUMA node, for example, thread doing eager page split is on different NUMA node compared to page it is splitting. Reviewers please provide suggestion to the following: 1. Module parameter is true by default, which means this feature will be enabled by default. Is this okay or should I set it to false? 2. I haven't reduced KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE considering that it might not be too much of an impact as only online nodes are filled during topup phase and in many cases some of these nodes will never be refilled again. Please let me know if you want this to be reduced. 3. I have tried to keep everything in x86/mmu except for some changes in virt/kvm/kvm_main.c. I used __weak function so that only x86/mmu will see the change, other arch nothing will change. I hope this is the right approach. 4. I am not sure what is the right way to split patch 2. If you think this is too big for a patch please let me know what would you prefer. Thanks Vipin v2: - All page table pages will be allocated on underlying physical page's NUMA node. - Introduced module parameter, numa_aware_pagetable, to disable this feature. - Using kvm_pfn_to_refcounted_page to get page from a pfn. v1: https://lore.kernel.org/all/20220801151928.270380-1-vipinsh@google.com/ Vipin Sharma (2): KVM: x86/mmu: Allocate page table pages on TDP splits during dirty log enable on the underlying page's numa node KVM: x86/mmu: Allocate page table pages on NUMA node of underlying pages arch/x86/include/asm/kvm_host.h | 4 +- arch/x86/kvm/mmu/mmu.c | 126 ++++++++++++++++++++++++-------- arch/x86/kvm/mmu/paging_tmpl.h | 4 +- arch/x86/kvm/mmu/tdp_mmu.c | 26 ++++--- include/linux/kvm_host.h | 17 +++++ include/linux/kvm_types.h | 2 + virt/kvm/kvm_main.c | 7 +- 7 files changed, 141 insertions(+), 45 deletions(-) base-commit: df0bb47baa95aad133820b149851d5b94cbc6790