This series is trying to bring the batched rmap removing to
try_to_unmap_one(). It's expected that the batched rmap
removing bring performance gain than remove rmap per page.
This series reconstruct the try_to_unmap_one() from:
loop:
clear and update PTE
unmap one page
goto loop
to:
loop:
clear and update PTE
goto loop
unmap the range of folio in one call
It is one step to always map/unmap the entire folio in one call.
Which can simplify the folio mapcount handling by avoid dealing
with each page map/unmap.
The changes are organized as:
Patch1/2 move the hugetlb and normal page unmap to dedicated
functions to make try_to_unmap_one() logic clearer and easy
to add batched rmap removing. To make code review easier, no
function change.
Patch3 cleanup the try_to_unmap_one_page(). Try to removed
some duplicated function calls.
Patch4 adds folio_remove_rmap_range() which batched remove rmap.
Patch5 make try_to_unmap_one() to batched remove rmap.
Testing done with the V3 patchset in a qemu guest
with 4G mem:
- kernel mm selftest to trigger vmscan() and final hit
try_to_unmap_one().
- Inject hwpoison to hugetlb page to trigger try_to_unmap_one()
call against hugetlb.
- 8 hours stress testing: Firefox + kernel mm selftest + kernel
build.
This series is based on next-20230303.
Changes from v2:
- General
- Rebase the patch to next-20230303
- Update cover letter about the preparation to unmap
the entire folio in one call
- No code change comparing to V2. But fix the patch applying
conflict because of wrong patch order in V2.
Changes from v1:
- General
- Rebase the patch to next-20230228
- Patch1
- Removed the if (PageHWPoison(page) && !(flags & TTU_HWPOISON)
as suggestion from Mike Kravetz and HORIGUCHI NAOYA
- Removed the mlock_drain_local() as suggestion from Mike Kravetz
_ Removed the comments about the mm counter change as suggestion
from Mike Kravetz
Yin Fengwei (5):
rmap: move hugetlb try_to_unmap to dedicated function
rmap: move page unmap operation to dedicated function
rmap: cleanup exit path of try_to_unmap_one_page()
rmap:addd folio_remove_rmap_range()
try_to_unmap_one: batched remove rmap, update folio refcount
include/linux/rmap.h | 5 +
mm/page_vma_mapped.c | 30 +++
mm/rmap.c | 623 +++++++++++++++++++++++++------------------
3 files changed, 398 insertions(+), 260 deletions(-)
--
2.30.2
