使用blktrace统计磁盘块I/O访问频率 + IO调度CFQ

http://blog.chinaunix.net/uid-24774106-id-4096470.html

http://blog.csdn.net/wyzxg/article/details/7449821

了解IO协议栈

[root@localhost ~]# stap -l 'ioscheduler.*'
ioscheduler.elv_add_request
ioscheduler.elv_completed_request
ioscheduler.elv_next_request

[root@localhost ~]# stap -l 'ioblock.*'
ioblock.end
ioblock.request

mount -t debugfs debugfs /sys/kernel/debug

btrace /dev/xvda1

[root@server1 ~]# btrace /dev/xvda1
,                 0.000000000     A  WS  +  <- (,)
,                 0.000002288     Q  WS  +  [jbd2/xvda1-]
,                 0.000008167     G  WS  +  [jbd2/xvda1-]
,                 0.000010829     I  WS  +  [jbd2/xvda1-]
^C202,                 0.000015747       m   N cfq225S / insert_request
,                 0.000016552       m   N cfq225S / add_to_rr
,                 0.000020871       m   N cfq workload slice:
,                 0.000021950       m   N cfq225S / set_active wl_prio: wl_type:
,                 0.000023149       m   N cfq225S / fifo=(null)
,                 0.000023724       m   N cfq225S / dispatch_insert
,                 0.000025445       m   N cfq225S / dispatched a request
,                 0.000026338       m   N cfq225S / activate rq, drv=
,                 0.000026463     D  WS  +  [jbd2/xvda1-]
,                 0.000034989     A  WS  +  <- (,)
,                 0.000035222     Q  WS  +  [jbd2/xvda1-]
,                 0.000035927     G  WS  +  [jbd2/xvda1-]
,                 0.000036342     I  WS  +  [jbd2/xvda1-]
,                 0.000036929       m   N cfq225S / insert_request
,                 0.000037721       m   N cfq225S / dispatch_insert
,                 0.000038336       m   N cfq225S / dispatched a request
,                 0.000038829       m   N cfq225S / activate rq, drv=
,                0.000039058     D  WS  +  [jbd2/xvda1-]
,                0.000040827     A  WS  +  <- (,)
,                0.000041061     Q  WS  +  [jbd2/xvda1-]
,                0.000041647     G  WS  +  [jbd2/xvda1-]
,                0.000041825     I  WS  +  [jbd2/xvda1-]
,                 0.000042266       m   N cfq225S / insert_request
,                 0.000042776       m   N cfq225S / dispatch_insert
,                 0.000043250       m   N cfq225S / dispatched a request
,                 0.000043626       m   N cfq225S / activate rq, drv=3
...

blktrace is a block layer IO tracing mechanism which provides detailed informa-tion about request queue operations up to user space.

      mount -t debugfs debugfs /sys/kernel/debug
      blktrace -d /dev/sda -o - |blkparse -i - -o blkparse.out

1. 

2. [root@server1 ~]# cat blkparse.out |grep cfq
   202,1 0 0 0.000015618 0 m N cfq225S / insert_request
   202,1 0 0 0.000020115 0 m N cfq225S / slice expired t=0
   202,1 0 0 0.000022817 0 m N cfq225S / sl_used=120 disp=7 charge=7 iops=1 sect=56
   202,1 0 0 0.000024892 0 m N cfq workload slice:100
   202,1 0 0 0.000025825 0 m N cfq225S / set_active wl_prio:0 wl_type:1
   202,1 0 0 0.000027072 0 m N cfq225S / fifo=(null)
   202,1 0 0 0.000027564 0 m N cfq225S / dispatch_insert
   202,1 0 0 0.000029452 0 m N cfq225S / dispatched a request
   202,1 0 0 0.000030065 0 m N cfq225S / activate rq, drv=1
   202,1 0 0 0.000041729 0 m N cfq225S / insert_request
   202,1 0 0 0.000042400 0 m N cfq225S / dispatch_insert
   202,1 0 0 0.000043012 0 m N cfq225S / dispatched a request
   202,1 0 0 0.000043463 0 m N cfq225S / activate rq, drv=2
   202,1 0 0 0.005256969 0 m N cfq225S / complete rqnoidle 1
   202,1 0 0 0.005258751 0 m N cfq225S / set_slice=120
   202,1 0 0 0.005263485 0 m N cfq225S / complete rqnoidle

3. ----------------

CFQ 调度

[root@server1 ~]# debugfs -R 'stats' /dev/xvda1
debugfs 1.41. (-May-)
Filesystem volume name:   <none>
Last mounted on:          /
Filesystem UUID:          94e4e384-0ace-437f-bc96-057dd64f42ee
Filesystem magic number:  0xEF53
Filesystem revision #:     (dynamic)
Filesystem features:      has_journal ext_attr resize_inode dir_index filetype needs_recovery extent flex_bg sparse_super large_
file huge_file uninit_bg dir_nlink extra_isize
Filesystem flags:         signed_directory_hash
Default mount options:    user_xattr acl
Filesystem state:         clean
Errors behavior:          Continue
Filesystem OS type:       Linux
Inode count:
Block count:
Reserved block count:
Free blocks:
Free inodes:
First block:
Block size:
Fragment size:
Reserved GDT blocks:
Blocks per group:
Fragments per group:
Inodes per group:
Inode blocks per group:
RAID stride:
Flex block group size:
Filesystem created:       Thu Aug  ::
Last mount time:          Tue Jun   ::
Last write time:          Sun Apr  ::
Mount count:
Maximum mount count:      -
Last checked:             Wed Jan  ::
Check interval:            (<none>)
Lifetime writes:           GB
Reserved blocks uid:       (user root)
Reserved blocks gid:       (group root)
First inode:
Inode size:
Required extra isize:
Desired extra isize:
Journal inode:
Default directory hash:   half_md4
Directory Hash Seed:      d5c54a86-d535-4c9b-9dea-e1b8e8088761
Journal backup:           inode blocks
Directories:
 Group  : block bitmap at , inode bitmap at , inode table at
            free blocks,  free inodes,  used directories,  unused inodes