From mboxrd@z Thu Jan  1 00:00:00 1970
From: Paolo Bonzini <pbonzini@redhat.com>
Subject: Re: How KVM hypervisor allocates physical pages to the VM.
Date: Wed, 17 Sep 2014 09:39:03 +0200
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Il 17/09/2014 05:56, Steven ha scritto:
> When size = 10MB and 20MB, it looks like that KVM use
> kmem_cache_alloc_node and kmalloc_node to allocate physical pages.
> However, when size = 40MB, KVM hypervisor uses mm_page_alloc to
> allocator physical pages. The former is based on the slab allocator,
> while the latter is directly from the buddy allocator.
> 
> So what is the heuristic used by the KVM to determine when to use the
> slab allocator or directly from the buddy allocator? Or is there
> anything wrong with my trace file? Thanks in advance.

I think you're simply tracking different things.  You should find the
symbols associated to the call sites.

KVM doesn't do anything special to allocate physical pages.  It simply
calls get_user_pages.

Paolo