Re: [PATCH v4 0/9] mmu notifier provide context informations
From: Christian KÃnig
Date: Fri Feb 01 2019 - 07:25:00 EST
Am 31.01.19 um 17:10 schrieb Jerome Glisse:
Andrew what is your plan for this ? I had a discussion with Peter Xu
and Andrea about change_pte() and kvm. Today the change_pte() kvm
optimization is effectively disabled because of invalidate_range
calls. With a minimal couple lines patch on top of this patchset
we can bring back the kvm change_pte optimization and we can also
optimize some other cases like for instance when write protecting
after fork (but i am not sure this is something qemu does often so
it might not help for real kvm workload).
I will be posting a the extra patch as an RFC, but in the meantime
i wanted to know what was the status for this.
Jan, Christian does your previous ACK still holds for this ?
At least the general approach still sounds perfectly sane to me.
Regarding how to merge these patches I think we should just get the
general infrastructure into Linus tree and when can then merge the DRM
patches one release later when we are sure that it doesn't break anything.
Christian.
On Wed, Jan 23, 2019 at 05:23:06PM -0500, jglisse@xxxxxxxxxx wrote:
From: JÃrÃme Glisse <jglisse@xxxxxxxxxx>
Hi Andrew, i see that you still have my event patch in you queue [1].
This patchset replace that single patch and is broken down in further
step so that it is easier to review and ascertain that no mistake were
made during mechanical changes. Here are the step:
Patch 1 - add the enum values
Patch 2 - coccinelle semantic patch to convert all call site of
mmu_notifier_range_init to default enum value and also
to passing down the vma when it is available
Patch 3 - update many call site to more accurate enum values
Patch 4 - add the information to the mmu_notifier_range struct
Patch 5 - helper to test if a range is updated to read only
All the remaining patches are update to various driver to demonstrate
how this new information get use by device driver. I build tested
with make all and make all minus everything that enable mmu notifier
ie building with MMU_NOTIFIER=no. Also tested with some radeon,amd
gpu and intel gpu.
If they are no objections i believe best plan would be to merge the
the first 5 patches (all mm changes) through your queue for 5.1 and
then to delay driver update to each individual driver tree for 5.2.
This will allow each individual device driver maintainer time to more
thouroughly test this more then my own testing.
Note that i also intend to use this feature further in nouveau and
HMM down the road. I also expect that other user like KVM might be
interested into leveraging this new information to optimize some of
there secondary page table invalidation.
Here is an explaination on the rational for this patchset:
CPU page table update can happens for many reasons, not only as a result
of a syscall (munmap(), mprotect(), mremap(), madvise(), ...) but also
as a result of kernel activities (memory compression, reclaim, migration,
...).
This patch introduce a set of enums that can be associated with each of
the events triggering a mmu notifier. Latter patches take advantages of
those enum values.
- UNMAP: munmap() or mremap()
- CLEAR: page table is cleared (migration, compaction, reclaim, ...)
- PROTECTION_VMA: change in access protections for the range
- PROTECTION_PAGE: change in access protections for page in the range
- SOFT_DIRTY: soft dirtyness tracking
Being able to identify munmap() and mremap() from other reasons why the
page table is cleared is important to allow user of mmu notifier to
update their own internal tracking structure accordingly (on munmap or
mremap it is not longer needed to track range of virtual address as it
becomes invalid).
[1] https://www.ozlabs.org/~akpm/mmotm/broken-out/mm-mmu_notifier-contextual-information-for-event-triggering-invalidation-v2.patch
Cc: Christian KÃnig <christian.koenig@xxxxxxx>
Cc: Jan Kara <jack@xxxxxxx>
Cc: Felix Kuehling <Felix.Kuehling@xxxxxxx>
Cc: Jason Gunthorpe <jgg@xxxxxxxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Matthew Wilcox <mawilcox@xxxxxxxxxxxxx>
Cc: Ross Zwisler <zwisler@xxxxxxxxxx>
Cc: Dan Williams <dan.j.williams@xxxxxxxxx>
Cc: Paolo Bonzini <pbonzini@xxxxxxxxxx>
Cc: Radim KrÄmÃÅ <rkrcmar@xxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxxxx>
Cc: Ralph Campbell <rcampbell@xxxxxxxxxx>
Cc: John Hubbard <jhubbard@xxxxxxxxxx>
Cc: kvm@xxxxxxxxxxxxxxx
Cc: dri-devel@xxxxxxxxxxxxxxxxxxxxx
Cc: linux-rdma@xxxxxxxxxxxxxxx
Cc: linux-fsdevel@xxxxxxxxxxxxxxx
Cc: Arnd Bergmann <arnd@xxxxxxxx>
JÃrÃme Glisse (9):
mm/mmu_notifier: contextual information for event enums
mm/mmu_notifier: contextual information for event triggering
invalidation
mm/mmu_notifier: use correct mmu_notifier events for each invalidation
mm/mmu_notifier: pass down vma and reasons why mmu notifier is
happening
mm/mmu_notifier: mmu_notifier_range_update_to_read_only() helper
gpu/drm/radeon: optimize out the case when a range is updated to read
only
gpu/drm/amdgpu: optimize out the case when a range is updated to read
only
gpu/drm/i915: optimize out the case when a range is updated to read
only
RDMA/umem_odp: optimize out the case when a range is updated to read
only
drivers/gpu/drm/amd/amdgpu/amdgpu_mn.c | 13 ++++++++
drivers/gpu/drm/i915/i915_gem_userptr.c | 16 ++++++++++
drivers/gpu/drm/radeon/radeon_mn.c | 13 ++++++++
drivers/infiniband/core/umem_odp.c | 22 +++++++++++--
fs/proc/task_mmu.c | 3 +-
include/linux/mmu_notifier.h | 42 ++++++++++++++++++++++++-
include/rdma/ib_umem_odp.h | 1 +
kernel/events/uprobes.c | 3 +-
mm/huge_memory.c | 14 +++++----
mm/hugetlb.c | 11 ++++---
mm/khugepaged.c | 3 +-
mm/ksm.c | 6 ++--
mm/madvise.c | 3 +-
mm/memory.c | 25 +++++++++------
mm/migrate.c | 5 ++-
mm/mmu_notifier.c | 10 ++++++
mm/mprotect.c | 4 ++-
mm/mremap.c | 3 +-
mm/oom_kill.c | 3 +-
mm/rmap.c | 6 ++--
20 files changed, 171 insertions(+), 35 deletions(-)
--
2.17.2
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