On Mon, Aug 19, 2024 at 12:59:26PM -0400, Kent Overstreet wrote:
> New data structure for tracking objects waiting on an RCU grace period.
> Supports regular RCU and SRCU, and possibly other RCU flavors in the
> future. Uses radix trees for tracking pending objects, falling back to
> linked lists on allocation failure.
>
> This gets us a more general replacement for SLAB_TYPESAFE_BY_RCU, and a
> cleaner and slightly faster backend for kvfree_call_rcu(), and
> in the future a faster backend for call_rcu() as well.
>
> There's still some small todo items, mentioned in the relevant patches.
>
> Paul - I'm considering putting this into 6.11 for bcachefs (not the
> patch that switches kvfree_rcu, of course), as I need it rather
> pressingly. Thoughts? I can put it in fs/bcachefs/ if you hate it :)
I am having a hard time imagining it being ready for inclusion in
kernel/rcu by the upcoming (v6.12) merge window, so if you need it then,
you will need to pull it into fs/bcachefs.
Don't get me wrong, it has improved since the June version. And we
can always move it later, if/when appropriate.
And yes, the kvfree_rcu() changes would need some serious performance
evaluation by the people who benefitted from the changes that make
kvfree_rcu() what it is today. So let's please defer that one.
Having the equivalent of SLAB_TYPESAFE_BY_SRCU could be attractive,
but I suspect that there are smaller changes that get us that with the
existing slab allocator.
Thanx, Paul
> Kent Overstreet (9):
> lib/generic-radix-tree.c: genradix_ptr_inlined()
> lib/generic-radix-tree.c: add preallocation
> darray: lift from bcachefs
> vmalloc: is_vmalloc_addr_inlined()
> rcu: delete lockdep_assert_irqs_enabled() assert in
> start_poll_synchronize_rcu_common()
> rcu: rcu_pending
> bcachefs: Rip out freelists from btree key cache
> bcachefs: key cache can now allocate from pending
> rcu: Switch kvfree_rcu() to new rcu_pending
>
> MAINTAINERS | 7 +
> fs/bcachefs/Makefile | 1 -
> fs/bcachefs/btree_key_cache.c | 406 +++----------
> fs/bcachefs/btree_key_cache_types.h | 18 +-
> fs/bcachefs/btree_node_scan_types.h | 2 +-
> fs/bcachefs/btree_types.h | 5 +-
> fs/bcachefs/btree_update.c | 2 +
> fs/bcachefs/btree_write_buffer_types.h | 2 +-
> fs/bcachefs/disk_accounting_types.h | 2 +-
> fs/bcachefs/fsck.c | 2 +-
> fs/bcachefs/journal_io.h | 2 +-
> fs/bcachefs/journal_sb.c | 2 +-
> fs/bcachefs/sb-downgrade.c | 3 +-
> fs/bcachefs/sb-errors_types.h | 2 +-
> fs/bcachefs/sb-members.h | 2 +-
> fs/bcachefs/subvolume.h | 1 -
> fs/bcachefs/subvolume_types.h | 2 +-
> fs/bcachefs/thread_with_file_types.h | 2 +-
> fs/bcachefs/util.h | 29 +-
> {fs/bcachefs => include/linux}/darray.h | 59 +-
> include/linux/darray_types.h | 22 +
> include/linux/generic-radix-tree.h | 106 +++-
> include/linux/mm.h | 7 +
> include/linux/rcu_pending.h | 27 +
> init/main.c | 2 +
> kernel/rcu/Makefile | 2 +-
> kernel/rcu/pending.c | 623 ++++++++++++++++++++
> kernel/rcu/tree.c | 747 ------------------------
> kernel/rcu/update.c | 1 -
> lib/Makefile | 2 +-
> {fs/bcachefs => lib}/darray.c | 12 +-
> lib/generic-radix-tree.c | 80 +--
> mm/vmalloc.c | 4 +-
> 33 files changed, 962 insertions(+), 1224 deletions(-)
> rename {fs/bcachefs => include/linux}/darray.h (66%)
> create mode 100644 include/linux/darray_types.h
> create mode 100644 include/linux/rcu_pending.h
> create mode 100644 kernel/rcu/pending.c
> rename {fs/bcachefs => lib}/darray.c (57%)
>
> --
> 2.45.2
>
