Ray Bryant wrote:
Hi Steve,
So in MTA there is only one policy, which is very similar to the BIND policy in
2.6.8.
MTA requires per mapped file policies. The patch I posted adds a
shared_policy tree to the address_space object, so that every file
can have it's own policy for page cache allocations. A mapped file
can have a tree of policies, one for each mapped region of the file,
for instance, text and initialized data. With the patch, file mapped
policies would work across all filesystems, and the specific support
in tmpfs and hugetlbfs can be removed.
The goal of MTA is to direct an entire program's resident pages (text
and data regions of the executable and all its shared libs) to a
single node or a specific set of nodes. The primary use of MTA (by
the customer) is to allow portions of memory to be powered off for
low power modes, and still have critical system applications running.
In MTA the executable file's policies are stored in the ELF image.
There is a utility to add a section containing the list of prefered nodes
for the executable's text and data regions. That section is parsed by
load_elf_binary(). The section data is in the form of mnemonic node
name strings, which load_elf_binary() converts to a node id list.
MTA also supports policies for the slab allocator.
(Just trying to figure out how to work both of our requirements into
the kernel in as simple as possible (but no simpler!) fashion.)
could we have both a global page cache policy as well as per file
policies. That is, if a mapped file has a policy, it overrides the
global policy. That would work fine for MTA.
Steve
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