iscsi: use dynamic single thread workqueue to improve performance

euleros inclusion
category: feature
feature: Implement NUMA affinity for order workqueue

-------------------------------------------------

On aarch64 NUMA machines, the kworker of iscsi created always jump
around across node boundaries. If it work on the different node even
different cpu package with the softirq of network interface, memcpy
with in iscsi_tcp_segment_recv will be slow down, and iscsi got an
terrible performance.

In this patch, we trace the cpu of softirq, and tell queue_work_on
to execute iscsi_xmitworker on the same NUMA node.

The performance data as below:
fio cmd:
fio -filename=/dev/disk/by-id/wwn-0x6883fd3100a2ad260036281700000000
-direct=1 -iodepth=32 -rw=read -bs=64k -size=30G -ioengine=libaio
-numjobs=1 -group_reporting -name=mytest -time_based -ramp_time=60
-runtime=60

before patch:
Jobs: 1 (f=1): [R] [52.5% done] [852.3MB/0KB/0KB /s] [13.7K/0/0 iops] [eta 00m:57s]
Jobs: 1 (f=1): [R] [53.3% done] [861.4MB/0KB/0KB /s] [13.8K/0/0 iops] [eta 00m:56s]
Jobs: 1 (f=1): [R] [54.2% done] [868.2MB/0KB/0KB /s] [13.9K/0/0 iops] [eta 00m:55s]

after pactch:
Jobs: 1 (f=1): [R] [53.3% done] [1070MB/0KB/0KB /s] [17.2K/0/0 iops] [eta 00m:56s]
Jobs: 1 (f=1): [R] [55.0% done] [1064MB/0KB/0KB /s] [17.3K/0/0 iops] [eta 00m:54s]
Jobs: 1 (f=1): [R] [56.7% done] [1069MB/0KB/0KB /s] [17.1K/0/0 iops] [eta 00m:52s]

cpu info:
Architecture:          aarch64
Byte Order:            Little Endian
CPU(s):                128
On-line CPU(s) list:   0-127
Thread(s) per core:    1
Core(s) per socket:    64
Socket(s):             2
NUMA node(s):          4
Model:                 0
CPU max MHz:           2600.0000
CPU min MHz:           200.0000
BogoMIPS:              200.00
L1d cache:             64K
L1i cache:             64K
L2 cache:              512K
L3 cache:              32768K
NUMA node0 CPU(s):     0-31
NUMA node1 CPU(s):     32-63
NUMA node2 CPU(s):     64-95
NUMA node3 CPU(s):     96-127

Signed-off-by: Biaoxiang Ye <yebiaoxiang@huawei.com>
Acked-by: Hanjun Guo <guohanjun@huawei.com>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>