On 01/06/2017 09:55 AM, Dave Hansen wrote:
On 01/06/2017 08:22 AM, Khalid Aziz wrote:
On 01/06/2017 08:36 AM, Dave Hansen wrote:
On 01/06/2017 07:32 AM, Khalid Aziz wrote:
I agree with you on simplicity first. Subpage granularity is complex,
but the architecture allows for subpage granularity. Maybe the right
approach is to support this at page granularity first for swappable
pages and then expand to subpage granularity in a subsequent patch?
Pages locked in memory can already use subpage granularity with my
patch.
What do you mean by "locked in memory"? mlock()'d memory can still be
migrated around and still requires "swap" ptes, for instance.
You are right. Page migration can invalidate subpage granularity even
for locked pages. Is it possible to use cpusets to keep a task and its
memory locked on a single node?
It's going to be hard to impossible to guarantee. mlock() doesn't
guarantee that things won't change physical addresses. You'd have to
change that guarantee or chase all the things in the kernel that might
change physical addresses (compaction, ksm, etc...).
Actually, that reminds me... How does your code interface with ksm? Or
is there no interaction needed since you're always working on virtual
addresses?
Yes, version tags are interpreted at virtual address level.
--
Khalid
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