[RFC PATCH 0/2] sbitmap: NUMA node spreading

[John Garry]

Hi Jens, guys,

I am sending this as an RFC to see if there is any future in it or ideas
on how to make better. I also need to improve some items (as mentioned in
2/2 commit message) and test a lot more.

The general idea is that we change from allocating a single array of
sbitmap words to allocating an sub-array per NUMA node. And then each CPU
in that node is hinted to use that sub-array

Initial performance looks decent.

Some figures:
System: 4-nodes (with memory on all nodes), 128 CPUs

null blk config block:
20 devs, submit_queues=NR_CPUS, shared_tags, shared_tag_bitmap,
hw_queue_depth=256

fio config:
bs=4096, iodepth=128, numjobs=10, cpus_allowed_policy=split, rw=read,
ioscheduler=none

Before:
7130K

After:
7630K

So a +7% IOPS gain.

Any comments welcome, thanks!.

Based on v5.18-rc6.

John Garry (2):
  sbitmap: Make sbitmap.map a double pointer
  sbitmap: Spread sbitmap word allocation over NUMA nodes

 include/linux/sbitmap.h | 16 +++++---
 lib/sbitmap.c           | 83 +++++++++++++++++++++++++++++++++--------
 2 files changed, 79 insertions(+), 20 deletions(-)

-- 
2.26.2