Hello Jens,
The blk-mq timeout handling rework that went upstream during the v4.18
development cycle introduced a performance regression due to the atomic
instructions that were added in the hot path. This patch series improves
blk-mq performance by reducing the number of atomic instructions in the
hot path. This patch series introduces the number of IOPS reported by the
following test with 15% (fifteen per cent) on an x86_64 system:
#!/bin/bash
if [ -e /sys/kernel/config/nullb ]; then
for d in /sys/kernel/config/nullb/*; do
[ -d "$d" ] && rmdir "$d"
done
fi
modprobe -r null_blk
[ -e /sys/module/null_blk ] && exit $?
modprobe null_blk nr_devices=0 &&
udevadm settle &&
cd /sys/kernel/config/nullb &&
mkdir nullb0 &&
cd nullb0 &&
echo 0 > completion_nsec &&
echo 4096 > blocksize &&
echo 0 > home_node &&
echo 1024 > size &&
echo 0 > memory_backed &&
echo 1 > power ||
exit $?
(
cd /sys/block/nullb0/queue &&
echo 2 > rq_affinity
) || exit $?
iodepth=${1:-1}
runtime=30
args=()
if [ "$iodepth" = 1 ]; then
args+=(--ioengine=psync)
else
args+=(--ioengine=libaio --iodepth_batch=$((iodepth/2)))
fi
args+=(--iodepth=$iodepth --name=nullb0 --filename=/dev/nullb0\
--rw=read --bs=4096 --loops=$((1<<20)) --direct=1 --numjobs=1 --thread\
--runtime=$runtime --invalidate=1 --gtod_reduce=1 --ioscheduler=none)
numactl -m 0 -N 0 -- fio "${args[@]}"
Bart Van Assche (5):
blk-mq: Rename BLK_EH_DONE into BLK_EH_DONT_RESET_TIMER
block: Remove a superfluous #include directive
block: Split blk_add_timer()
block: Simplify blk_add_timer() and blk_mq_add_timer()
blk-mq: Rework blk-mq timeout handling again
Documentation/scsi/scsi_eh.txt | 4 +-
block/blk-core.c | 3 +
block/blk-mq-debugfs.c | 3 +-
block/blk-mq.c | 284 ++++++++++++++++------
block/blk-mq.h | 10 +-
block/blk-timeout.c | 109 +++++----
block/blk.h | 1 +
drivers/block/mtip32xx/mtip32xx.c | 2 +-
drivers/block/nbd.c | 4 +-
drivers/block/null_blk_main.c | 4 +-
drivers/message/fusion/mptsas.c | 2 +-
drivers/mmc/core/queue.c | 2 +-
drivers/nvme/host/pci.c | 10 +-
drivers/nvme/host/rdma.c | 2 +-
drivers/nvme/target/loop.c | 2 +-
drivers/s390/block/dasd.c | 6 +-
drivers/scsi/gdth.c | 2 +-
drivers/scsi/libiscsi.c | 6 +-
drivers/scsi/megaraid/megaraid_sas_base.c | 2 +-
drivers/scsi/mvumi.c | 2 +-
drivers/scsi/qla4xxx/ql4_os.c | 2 +-
drivers/scsi/scsi_error.c | 18 +-
drivers/scsi/scsi_transport_fc.c | 4 +-
drivers/scsi/scsi_transport_srp.c | 4 +-
drivers/scsi/ufs/ufshcd.c | 6 +-
include/linux/blk-mq.h | 14 --
include/linux/blkdev.h | 52 +++-
27 files changed, 367 insertions(+), 193 deletions(-)
--
2.18.0
