Re: [PATCH 2/2] kvm/e500v2: mapping guest TLB1 to host TLB0

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Liu, ping?


On 10.09.2010, at 01:24, Alexander Graf wrote:

> 
> On 08.09.2010, at 11:40, Liu Yu wrote:
> 
>> Current guest TLB1 is mapped to host TLB1.
>> As host kernel only provides 4K uncontinuous pages,
>> we have to break guest large mapping into 4K shadow mappings.
>> These 4K shadow mappings are then mapped into host TLB1 on fly.
>> As host TLB1 only has 13 free entries, there's serious tlb miss.
>> 
>> Since e500v2 has a big number of TLB0 entries,
>> it should be help to map those 4K shadow mappings to host TLB0.
>> To achieve this, we need to unlink guest tlb and host tlb,
>> So that guest TLB1 mappings can route to any host TLB0 entries freely.
>> 
>> Pages/mappings are considerred in the same kind as host tlb entry.
>> This patch remove the link between pages and guest tlb entry to do the unlink.
>> And keep host_tlb0_ref in each vcpu to trace pages.
>> Then it's easy to map guest TLB1 to host TLB0.
>> 
>> In guest ramdisk boot test(guest mainly uses TLB1),
>> with this patch, the tlb miss number get down 90%.
>> 
>> Signed-off-by: Liu Yu <yu.liu@xxxxxxxxxxxxx>
>> ---
>> arch/powerpc/include/asm/kvm_e500.h |    7 +-
>> arch/powerpc/kvm/e500.c             |    4 +
>> arch/powerpc/kvm/e500_tlb.c         |  280 ++++++++++++-----------------------
>> arch/powerpc/kvm/e500_tlb.h         |    1 +
>> 4 files changed, 104 insertions(+), 188 deletions(-)

[snip]


Alex--
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