On Tue, 2007-06-05 at 22:17 +0800, Avi Kivity wrote: > Shaohua Li wrote: > > Hi, > > This is a updated patch set of swap out kvm guest pages.Changes are: > > 1. refresh against to kvm-26 > > 2. clean up shadow page handling to make gfn_to_page not be called > > within kmap_atomic/kunamp_atomic. > > 3. variant bug fixing. Now the patch is quite stable in my test. > > 4. make swap out optional. A compile option can completely close > swap > > out. There should be no performance impact if swapout isn't enabled. > > > > There are still a lot of unresolved issues: > > 1. just work for one vm. waiting for kvm hook into scheduler > > 2. Not work for mp guest and can't swap out pages which shadow page > > table point to, this require kvm .flush_tlb can send ipi to vcpu. > > 3. swapoff isn't supported. We need a hook to sys_swapoff for kvm. > > > > Please review, suggests and comments are welcome. > > > > > > The patch rmaps read-only guest pages. While this is of course > required, it will make unshadowing ptes pointing to shared library > pages > very expensive. If we have a guest with 200 processes, all mapping > glibc, then an exit() will have to walk a linear list of size 200 per > shadowed pte. I'm doing performance test currently, will update you soon. > Do you know how the Linux rmap implementation handles this? In Linux, you can get the address_space from the page, then get all vmas of the address_space, then walking the page tables of all the vmas.It's also a linear list walking, I think.
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