On 05/10/2012 05:33 PM, Takuya Yoshikawa wrote: > From: Takuya Yoshikawa <[email protected]> > > lpage_info is created for each large level even when the memory slot is > not for RAM. This means that when we add one slot for a PCI device, we > end up allocating at least KVM_NR_PAGE_SIZES - 1 pages by vmalloc(): > this problem will become severer if we support more guests with more > devices in the future. > > Although it is not easy to differentiate RAM slots from others, we can > avoid wasting pages by making KVM_NR_PAGE_SIZES - 1 lpage_info arrays > coalesce into one and using kmalloc() when the result is small enough. > > Signed-off-by: Takuya Yoshikawa <[email protected]> > --- > arch/x86/kvm/x86.c | 56 ++++++++++++++++++++++++++++++--------------------- > 1 files changed, 33 insertions(+), 23 deletions(-) > > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > index 4de705c..716d543 100644 > --- a/arch/x86/kvm/x86.c > +++ b/arch/x86/kvm/x86.c > @@ -6300,35 +6300,52 @@ void kvm_arch_free_memslot(struct kvm_memory_slot > *free, > { > int i; > > - for (i = 0; i < KVM_NR_PAGE_SIZES - 1; ++i) { > - if (!dont || free->arch.lpage_info[i] != > dont->arch.lpage_info[i]) { > - vfree(free->arch.lpage_info[i]); > - free->arch.lpage_info[i] = NULL; > - } > - } > + if (dont && free->arch.lpage_info[0] == dont->arch.lpage_info[0]) > + return; > + > + if (is_vmalloc_addr(free->arch.lpage_info[0])) > + vfree(free->arch.lpage_info[0]); > + else > + kfree(free->arch.lpage_info[0]); > + > + for (i = 0; i < KVM_NR_PAGE_SIZES - 1; ++i) > + free->arch.lpage_info[i] = NULL; > } >
I don't feel that the savings is worth the extra complication. We save two pages per memslot here. What about using kvmalloc() instead of vmalloc()? It's in security/apparmor now, but can be made generic. -- error compiling committee.c: too many arguments to function -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
