Re: [patch 2/3 v4]raid1: read balance chooses idlest disk for SSD

[Roberto Spadim <roberto@xxxxxxxxxxxxx>]

well, i´m thinking something like elevators, they have some files to
configure options at /sys/block/sda/xxxx, it´s a nice interface...
echo and cat to configure the elevator or sysctl...

check this example of md in a old linux kernel (i don´t remember
version maybe 2.6.18)



#cd /sys/block/md0/md
# ls -l
-rw-r--r-- 1 root root 4096 Jul  5 23:39 array_state
--w------- 1 root root 4096 Jul  5 23:39 bitmap_set_bits
-rw-r--r-- 1 root root 4096 Jul  5 23:39 chunk_size
-rw-r--r-- 1 root root 4096 Jul  5 23:39 component_size
-r--r--r-- 1 root root 4096 Jul  5 23:39 degraded
drwxr-xr-x 2 root root    0 Jul  5 23:39 dev-sda1 <<<<=====
drwxr-xr-x 2 root root    0 Jul  5 23:39 dev-sdb1 <<<<=====
-rw-r--r-- 1 root root 4096 Jul  5 23:39 layout
-rw-r--r-- 1 root root 4096 Jul  5 23:39 level
-rw-r--r-- 1 root root 4096 Jul  5 23:39 metadata_version
-r--r--r-- 1 root root 4096 Jul  5 23:39 mismatch_cnt
--w------- 1 root root 4096 Jul  5 23:39 new_dev
-rw-r--r-- 1 root root 4096 Jul  5 23:39 raid_disks
lrwxrwxrwx 1 root root    0 Jul  5 23:39 rd2 -> dev-sda1
lrwxrwxrwx 1 root root    0 Jul  5 23:39 rd3 -> dev-sdb1
-rw-r--r-- 1 root root 4096 Jul  5 23:39 reshape_position
-rw-r--r-- 1 root root 4096 Jul  5 23:39 resync_start
-rw-r--r-- 1 root root 4096 Jul  5 23:39 safe_mode_delay
-rw-r--r-- 1 root root 4096 Jul  5 23:39 suspend_hi
-rw-r--r-- 1 root root 4096 Jul  5 23:39 suspend_lo
-rw-r--r-- 1 root root 4096 Jul  5 23:39 sync_action
-r--r--r-- 1 root root 4096 Jul  5 23:39 sync_completed
-rw-r--r-- 1 root root 4096 Jul  5 23:39 sync_force_parallel
-rw-r--r-- 1 root root 4096 Jul  5 23:39 sync_max
-r--r--r-- 1 root root 4096 Jul  5 23:39 sync_speed
-rw-r--r-- 1 root root 4096 Jul  5 23:39 sync_speed_max
-rw-r--r-- 1 root root 4096 Jul  5 23:39 sync_speed_min


# ls dev-sda1/ -l
total 0
lrwxrwxrwx 1 root root    0 Jul  5 23:40 block -> ../../../sda/sda1
-rw-r--r-- 1 root root 4096 Jul  5 23:40 errors
-rw-r--r-- 1 root root 4096 Jul  5 23:40 offset
-rw-r--r-- 1 root root 4096 Jul  5 23:40 size
-rw-r--r-- 1 root root 4096 Jul  5 23:40 slot
-rw-r--r-- 1 root root 4096 Jul  5 23:40 state
--->>> maybe here we could put a file called: "raid1_read_balance_disk_speed"


maybe we could save this information at md metadata? i don´t know how
it works, just a idea, instead saving it at sysctl, use md metadata
informations...

-- 
Roberto Spadim
Spadim Technology / SPAEmpresarial
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