Re: [PATCH v7 0/6] vfs: Use dlock list for SB's s_inodes list

[Waiman Long <longman@redhat.com>]

On 10/05/2017 02:43 PM, Waiman Long wrote:
>
> This is a follow up of the following patchset:
>
>   [PATCH v7 0/4] vfs: Use per-cpu list for SB's s_inodes list
>   https://lkml.org/lkml/2016/4/12/1009
>
> This patchset provides new APIs for a set of distributed locked lists
> (one/CPU core) to minimize lock and cacheline contention. Insertion
> and deletion to the list will be cheap and relatively contention free.
> Lookup, on the other hand, may be a bit more costly as there are
> multiple lists to iterate. This is not really a problem for the
> replacement of superblock's inode list by dlock list included in
> the patchset as lookup isn't needed.
>
> For use cases that need to do lookup, the dlock list can also be
> treated as a set of hashed lists that scales with the number of CPU
> cores in the system.
>
> Both patches 5 and 6 are added to support other use cases like epoll
> nested callbacks, for example, which could use the dlock-list to
> reduce lock contention problem.
>
> Patch 1 introduces the dlock list. The list heads are allocated
> by kcalloc() instead of percpu_alloc(). Each list head entry is
> cacheline aligned to minimize contention.
>
> Patch 2 replaces the use of list_for_each_entry_safe() in
> evict_inodes() and invalidate_inodes() by list_for_each_entry().
>
> Patch 3 modifies the superblock and inode structures to use the dlock
> list. The corresponding functions that reference those structures
> are modified.
>
> Patch 4 makes the sibling CPUs use the same dlock list head to reduce
> the number of list heads that need to be iterated.
>
> Patch 5 enables alternative use case of as a set of hashed lists.
>
> Patch 6 provides an irq safe mode specified at dlock-list allocation
> time so that it can be within interrupt context.
>
> Jan Kara (1):
>   vfs: Remove unnecessary list_for_each_entry_safe() variants
>
> Waiman Long (5):
>   lib/dlock-list: Distributed and lock-protected lists
>   vfs: Use dlock list for superblock's inode list
>   lib/dlock-list: Make sibling CPUs share the same linked list
>   lib/dlock-list: Enable faster lookup with hashing
>   lib/dlock-list: Add an IRQ-safe mode to be used in interrupt handler
>
>  fs/block_dev.c             |   9 +-
>  fs/drop_caches.c           |   9 +-
>  fs/inode.c                 |  38 +++---
>  fs/notify/fsnotify.c       |   9 +-
>  fs/quota/dquot.c           |  14 +-
>  fs/super.c                 |   7 +-
>  include/linux/dlock-list.h | 245 ++++++++++++++++++++++++++++++++++
>  include/linux/fs.h         |   8 +-
>  lib/Makefile               |   2 +-
>  lib/dlock-list.c           | 322 +++++++++++++++++++++++++++++++++++++++++++++
>  10 files changed, 609 insertions(+), 54 deletions(-)
>  create mode 100644 include/linux/dlock-list.h
>  create mode 100644 lib/dlock-list.c
>
Is there other objections about merging this patch series? With the
additional patches 8 & 9 that I sent out on Oct 17, I think I had
addressed all the concerns that I received so far. Please let me know
what else do I need to do to make these patches mergeable?

Thanks,
Longman