On 2024/6/6 16:38, David Hildenbrand wrote:
On 06.06.24 05:31, Baolin Wang wrote:
On 2024/6/4 20:05, Daniel Gomez wrote:
On Tue, Jun 04, 2024 at 05:45:20PM +0800, Baolin Wang wrote:
On 2024/6/4 16:18, Daniel Gomez wrote:
On Fri, May 31, 2024 at 01:13:48PM +0200, David Hildenbrand wrote:
As a default, we should not be using large folios / mTHP for any
shmem,
just like we did with THP via shmem_enabled. This is what this
series
currently does, and is aprt of the whole mTHP user-space
interface design.
Further, the mTHP controls should control all of shmem, not only
"anonymous shmem".
Yes, that's what I thought and in my TODO list.
Good, it would be helpful to coordinate with Daniel and Pankaj.
I've integrated patches 11 and 12 from the lsf RFC thread [1] on
top of Baolin's
v3 patches. You may find a version in my integration branch here
[2]. I can
attach them here if it's preferred.
[1]
https://lore.kernel.org/all/20240515055719.32577-1-da.gomez@xxxxxxxxxxx/
[2]
https://protect2.fireeye.com/v1/url?k=a23e7c06-c3b56926-a23ff749-74fe485fb347-371ca2bfd5d9869f&q=1&e=6974304e-a786-4255-93a7-57498540241c&u=https%3A%2F%2Fgitlab.com%2Fdkruces%2Flinux-next%2F-%2Fcommits%2Fnext-20240604-shmem-mthp
The point here is to combine the large folios strategy I proposed
with mTHP
user controls. Would it make sense to limit the orders to the
mapping order
calculated based on the size and index?
IMO, for !anon shmem, this change makes sense to me. We should
respect the
size and mTHP should act as a order filter.
What about respecing the size when within_size flag is enabled? Then,
'always'
would allocate mTHP enabled folios, regardless of the size. And 'never'
would ignore mTHP and size. So, 'never' can be used for this 'safe'
boot case
mentioned in the discussion.
Looks reasonable to me. What do you think, David?
That mimics existing PMD-THP behavior, right?
With "within_size", we must not exceed the size, with "always", we may
exceed the size.
Yes, I think so.
And what about 'advise' option? Silimar to 'within_size'?
Good question. What's the behavior of PMD-THP? I would assume it behaves
like "within_size", because in the common case we mmap (+advise) only
within the size of the file, not exceeding it.
Yes, that is also my understanding.
(the always option, as I learned during the meeting, is primarily
helpful when writing to tmpfs files in an append-fashion. With
mmap()+madvise() that doesn't quite happen)
