From: Omar Sandoval <osandov@xxxxxx> This patch series implements an I/O scheduler for multiqueue devices combining several techniques: the scalable bitmap library, the new blk-stats API, and queue depth throttling similar to blk-wbt. These patches are on top of my earlier blk-stats series [1]. They also need a fix in Jens' for-linus branch in order to work properly [2]. Patches 1 and 2 implement a new sbitmap operation and patch 3 exports a required function. Patch 4 implements the new scheduler, named Kyber. The commit message in patch 4 describes Kyber in detail. The scheduler employs some heuristics that I've experimented with, but that's probably the area that needs the most work. I'll be at LSF/MM next week, and there's currently a lightning talk on the schedule to discuss improvements and extensions. A quick test case that demonstrates the scheduler in action: --- [global] filename=/dev/nvme0n1 direct=1 runtime=10s time_based group_reporting [writers] numjobs=40 ioengine=libaio iodepth=1024 rw=randwrite [reader] new_group rate_iops=1000 ioengine=sync rw=randread --- With Kyber set to a target latency of 1 ms, the reader sees latencies of 8 ms on average. Kyber brings this down to just over 1 ms. Thanks! 1: http://marc.info/?l=linux-block&m=148952547205774&w=2 2: http://git.kernel.dk/cgit/linux-block/commit/?h=for-linus&id=efd4b81abbe1ac753717f2f10cd3dab8bed6c103 Omar Sandoval (4): sbitmap: add sbitmap_get_shallow() operation blk-mq: add shallow depth option for blk_mq_get_tag() blk-mq: export blk_mq_finish_request() blk-mq: introduce Kyber multiqueue I/O scheduler block/Kconfig.iosched | 8 + block/Makefile | 1 + block/blk-mq-tag.c | 5 +- block/blk-mq.c | 1 + block/blk-mq.h | 1 + block/elevator.c | 9 +- block/kyber-iosched.c | 586 ++++++++++++++++++++++++++++++++++++++++++++++++ include/linux/sbitmap.h | 55 +++++ lib/sbitmap.c | 75 ++++++- 9 files changed, 729 insertions(+), 12 deletions(-) create mode 100644 block/kyber-iosched.c -- 2.12.0
