Andrew Morton wrote:
On Mon, 20 Apr 2009 04:36:06 +0300
Izik Eidus <ieidus@xxxxxxxxxx> wrote:
Ksm is driver that allow merging identical pages between one or more
applications in way unvisible to the application that use it.
Pages that are merged are marked as readonly and are COWed when any
application try to change them.
Breaks sparc64 and probably lots of other architectures:
mm/ksm.c: In function `try_to_merge_two_pages_alloc':
mm/ksm.c:697: error: `_PAGE_RW' undeclared (first use in this function)
there should be an official arch-independent way of manipulating
vma->vm_page_prot, but I'm not immediately finding it.
Hi,
vm_get_page_prot() will probably do the work.
I will send you patch that fix it,
but first i am waiting for Andrea and Chris to say they are happy with
small changes that i made to the api after conversation i had with them
(about checking if this api is robust enough so we wont have to change
it later)
When i will get their acks, i will send you patch against this togather
with the api (until then it is ok to just leave it only for x86)
changes are:
1) limiting the number of memory regions registered per file descriptor
- so while (1){ (ioctl(KSM_REGISTER_MEMORY_REGION()) ) wont omm the host
2) checking if memory is overlap in registration (more effective to
ignore such cases)
3) allow removing specific memoy regions inside fd.
Thanks.
An alternative (and quite inferior) "fix" would be to disable ksm on
architectures which don't implement _PAGE_RW. That's most of them.
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