Re: [RFC][PATCH v2 11/21] kvm: allocate page table pages from DRAM

[Dave Hansen <dave.hansen@intel.com>]

On 12/26/18 5:14 AM, Fengguang Wu wrote:
> +static unsigned long __get_dram_free_pages(gfp_t gfp_mask)
> +{
> +       struct page *page;
> +
> +       page = __alloc_pages(GFP_KERNEL_ACCOUNT, 0, numa_node_id());
> +       if (!page)
> +	       return 0;
> +       return (unsigned long) page_address(page);
> +}

There seems to be a ton of *policy* baked into these patches.  For
instance: thou shalt not allocate page tables pages from PMEM.  That's
surely not a policy we want to inflict on every Linux user until the end
of time.

I think the more important question is how we can have the specific
policy that this patch implements, but also leave open room for other
policies, such as: "I don't care how slow this VM runs, minimize the
amount of fast memory it eats."