Christian Bornträger wrote:
Am Mittwoch 20 Mai 2009 10:45:50 schrieb Avi Kivity:
Christian Bornträger wrote:
o shared guest kernels: The CMS operating system is build as a bootable
DCSS (called named-saved-segments NSS). All guests have the same host
pages for the read-only parts of the CMS kernel. The local data is stored
in exclusive-write parts of the same NSS. Linux on System z is also
capable of using this feature (CONFIG_SHARED_KERNEL). The kernel linkage
is changed in a way to separate the read-only text segment from the other
parts with segment size alignment
How does patching (smp, kprobes/jprobes, markers/ftrace) work with this?
It does not. :-)
Because of that and since most distro kernels are fully modular and kernel
updates are another problem this feature is not used very often for Linux. It
is used heavily in CMS, though.
Actually, we could do COW in the host but then it is really not worth the
effort.
ksm on low throttle would solve all of those problems.
Yes, KSM is easier and it even finds duplicate data pages.
On the other hand it does only provide memory saving. It does not speedup
application startup like execute-in-place (major page faults become minor page
faults for text pages if the page is already backed by the host)
I am not claiming that KSM is useless. Depending on the scenario you might
want the one or the other or even both. For typical desktop use, KSM is very
likely the better approach
If ksm shares pagecache, then doesn't it become effectively XIP?
We could also hook virtio dma to preemptively share pages somehow.
--
error compiling committee.c: too many arguments to function
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