内核：3.8.13
ARM: IBOX 4412
camera分辨率 640x480
160000（1.6G）时4核全开，
echo Peformance > scaling_governor
Mem: 58220K used, 969844K free, 0K shrd, 268K buff, 2524K cached
CPU: 49.7% usr 1.4% sys 0.0% nic 48.7% idle 0.0% io 0.0% irq 0.0% sirq
Load average: 1.01 0.67 0.30 2/59 1427
PID PPID USER STAT VSZ %VSZ CPU %CPU COMMAND
1412 1399 0 R 5004 0.4 0 49.7 ./cam_previewfb0v3
1427 1399 0 R 2392 0.2 1 1.4 top -d1
1399 1 0 S 2392 0.2 0 0.0 -/bin/sh
1 0 0 S 2388 0.2 3 0.0 init
372 2 0 SW 0 0.0 0 0.0 [khubd]
34 2 0 SW 0 0.0 1 0.0 [kworker/1:1]
6 2 0 SW 0 0.0 1 0.0 [kworker/u:0]
16 2 0 RW 0 0.0 2 0.0 [ksoftirqd/2]
9 2 0 SW 0 0.0 1 0.0 [rcu_preempt]
13 2 0 SW 0 0.0 1 0.0 [migration/1]
1356 2 0 SW 0 0.0 0 0.0 [kworker/0:3]
1324 2 0 SW 0 0.0 0 0.0 [mmcqd/0]
26 2 0 SW 0 0.0 1 0.0 [kdevtmpfs]
2 0 0 SW 0 0.0 1 0.0 [kthreadd]
3 2 0 SW 0 0.0 0 0.0 [ksoftirqd/0]
4 2 0 SW 0 0.0 0 0.0 [kworker/0:0]
5 2 0 SW< 0 0.0 0 0.0 [kworker/0:0H]
7 2 0 SW< 0 0.0 0 0.0 [kworker/u:0H]
8 2 0 SW 0 0.0 0 0.0 [migration/0]
10 2 0 SW 0 0.0 0 0.0 [rcu_bh]
最大频率设置1G时，4核全开
Mem: 59380K used, 968684K free, 0K shrd, 272K buff, 2524K cached
CPU: 24.6% usr 0.2% sys 0.0% nic 74.8% idle 0.2% io 0.0% irq 0.0% sirq
Load average: 0.82 0.79 0.48 2/61 1471
PID PPID USER STAT VSZ %VSZ CPU %CPU COMMAND
1412 1399 0 R 5004 0.4 0 24.6 ./cam_previewfb0v3
1471 1399 0 R 2392 0.2 3 0.2 top -d1
1399 1 0 S 2392 0.2 1 0.0 -/bin/sh
1 0 0 S 2388 0.2 3 0.0 init
34 2 0 SW 0 0.0 1 0.0 [kworker/1:1]
372 2 0 SW 0 0.0 0 0.0 [khubd]
1356 2 0 SW 0 0.0 0 0.0 [kworker/0:3]
6 2 0 SW 0 0.0 2 0.0 [kworker/u:0]
16 2 0 SW 0 0.0 2 0.0 [ksoftirqd/2]
9 2 0 SW 0 0.0 3 0.0 [rcu_preempt]
1324 2 0 SW 0 0.0 3 0.0 [mmcqd/0]
13 2 0 SW 0 0.0 1 0.0 [migration/1]
26 2 0 SW 0 0.0 1 0.0 [kdevtmpfs]
35 2 0 SW 0 0.0 2 0.0 [kworker/2:1]
37 2 0 SW 0 0.0 3 0.0 [kworker/3:1]
1385 2 0 SW 0 0.0 1 0.0 [jbd2/mmcblk1p3-]
1411 2 0 SW 0 0.0 1 0.0 [flush⑴79:0]
2 0 0 SW 0 0.0 1 0.0 [kthreadd]
3 2 0 SW 0 0.0 0 0.0 [ksoftirqd/0]
4 2 0 SW 0 0.0 0 0.0 [kworker/0:0]
最大频率设置1G时，开3个核
Mem: 59080K used, 968984K free, 0K shrd, 288K buff, 2524K cached
CPU: 32.7% usr 0.3% sys 0.0% nic 66.8% idle 0.0% io 0.0% irq 0.0% sirq
Load average: 0.91 0.82 0.52 2/60 1477
PID PPID USER STAT VSZ %VSZ CPU %CPU COMMAND
1412 1399 0 R 5004 0.4 0 32.7 ./cam_previewfb0v3
1477 1399 0 R 2392 0.2 3 0.3 top -d1
1399 1 0 S 2392 0.2 3 0.0 -/bin/sh
1 0 0 S 2388 0.2 3 0.0 init
34 2 0 SW 0 0.0 1 0.0 [kworker/1:1]
372 2 0 SW 0 0.0 0 0.0 [khubd]
1356 2 0 SW 0 0.0 0 0.0 [kworker/0:3]
6 2 0 SW 0 0.0 2 0.0 [kworker/u:0]
16 2 0 SW 0 0.0 2 0.0 [ksoftirqd/2]
9 2 0 SW 0 0.0 3 0.0 [rcu_preempt]
1324 2 0 SW 0 0.0 3 0.0 [mmcqd/0]
35 2 0 SW 0 0.0 2 0.0 [kworker/2:1]
26 2 0 SW 0 0.0 1 0.0 [kdevtmpfs]
37 2 0 SW 0 0.0 3 0.0 [kworker/3:1]
1385 2 0 SW 0 0.0 2 0.0 [jbd2/mmcblk1p3-]
1411 2 0 SW 0 0.0 2 0.0 [flush⑴79:0]
2 0 0 SW 0 0.0 1 0.0 [kthreadd]
3 2 0 SW 0 0.0 0 0.0 [ksoftirqd/0]
4 2 0 SW 0 0.0 0 0.0 [kworker/0:0]
5 2 0 SW< 0 0.0 0 0.0 [kworker/0:0H]
最大频率设置1G，只打开1个核
Mem: 57916K used, 970148K free, 0K shrd, 300K buff, 2524K cached
CPU: 68.3% usr 0.0% sys 0.0% nic 31.6% idle 0.0% io 0.0% irq 0.0% sirq
Load average: 0.76 0.80 0.53 2/58 1481
PID PPID USER STAT VSZ %VSZ CPU %CPU COMMAND
1412 1399 0 R 5004 0.4 0 67.2 ./cam_previewfb0v3
1481 1399 0 R 2392 0.2 0 0.9 top -d1
1399 1 0 S 2392 0.2 0 0.0 -/bin/sh
1 0 0 S 2388 0.2 3 0.0 init
34 2 0 SW 0 0.0 1 0.0 [kworker/1:1]
372 2 0 SW 0 0.0 0 0.0 [khubd]
1356 2 0 SW 0 0.0 0 0.0 [kworker/0:3]
6 2 0 SW 0 0.0 0 0.0 [kworker/u:0]
16 2 0 RW 0 0.0 2 0.0 [ksoftirqd/2]
9 2 0 SW 0 0.0 0 0.0 [rcu_preempt]
1324 2 0 SW 0 0.0 0 0.0 [mmcqd/0]
35 2 0 SW 0 0.0 2 0.0 [kworker/2:1]
1385 2 0 SW 0 0.0 0 0.0 [jbd2/mmcblk1p3-]
26 2 0 SW 0 0.0 1 0.0 [kdevtmpfs]
37 2 0 SW 0 0.0 3 0.0 [kworker/3:1]
1411 2 0 SW 0 0.0 0 0.0 [flush⑴79:0]
2 0 0 SW 0 0.0 1 0.0 [kthreadd]
3 2 0 SW 0 0.0 0 0.0 [ksoftirqd/0]
4 2 0 SW 0 0.0 0 0.0 [kworker/0:0]
5 2 0 SW< 0 0.0 0 0.0 [kworker/0:0H]
最低性能模式时， 频率200MHz，只开了两个核（lcd预览画面10分卡顿）
echo powersave > cpu0/cpufreq/scaling_governor
CPU3: shutdown
CPU2: shutdown
Mem: 58672K used, 969392K free, 0K shrd, 340K buff, 2524K cached
CPU: 49.7% usr 1.9% sys 0.0% nic 48.3% idle 0.0% io 0.0% irq 0.0% sirq
Load average: 0.99 0.80 0.65 2/59 1495
PID PPID USER STAT VSZ %VSZ CPU %CPU COMMAND
1412 1399 0 R 5004 0.4 0 49.7 ./cam_previewfb0v3
1495 1399 0 R 2392 0.2 1 1.4 top -d1
1399 1 0 S 2392 0.2 1 0.0 -/bin/sh
1 0 0 S 2388 0.2 3 0.0 init
34 2 0 SW 0 0.0 1 0.0 [kworker/1:1]
372 2 0 SW 0 0.0 0 0.0 [khubd]
1356 2 0 SW 0 0.0 0 0.0 [kworker/0:3]
6 2 0 SW 0 0.0 3 0.0 [kworker/u:0]
4 2 0 SW 0 0.0 0 0.0 [kworker/0:0]
9 2 0 SW 0 0.0 1 0.0 [rcu_preempt]
16 2 0 RW 0 0.0 2 0.0 [ksoftirqd/2]
1324 2 0 SW 0 0.0 1 0.0 [mmcqd/0]
35 2 0 SW 0 0.0 2 0.0 [kworker/2:1]
37 2 0 SW 0 0.0 3 0.0 [kworker/3:1]
1385 2 0 SW 0 0.0 1 0.0 [jbd2/mmcblk1p3-]
1411 2 0 SW 0 0.0 1 0.0 [flush⑴79:0]
14 2 0 SW 0 0.0 1 0.0 [kworker/1:0]
26 2 0 SW 0 0.0 1 0.0 [kdevtmpfs]
2 0 0 SW 0 0.0 0 0.0 [kthreadd]
3 2 0 SW 0 0.0 0 0.0 [ksoftirqd/0]
最低性能模式，200MHz， 只打开1个核（画面卡顿，几近满负荷运行）
Mem: 58020K used, 970044K free, 0K shrd, 352K buff, 2524K cached
CPU: 97.1% usr 2.8% sys 0.0% nic 0.0% idle 0.0% io 0.0% irq 0.0% sirq
Load average: 1.00 0.87 0.69 2/58 1500
PID PPID USER STAT VSZ %VSZ CPU %CPU COMMAND
1412 1399 0 R 5004 0.4 0 97.0 ./cam_previewfb0v3
1500 1399 0 R 2392 0.2 0 2.8 top -d1
1399 1 0 S 2392 0.2 0 0.0 -/bin/sh
1 0 0 S 2388 0.2 3 0.0 init
34 2 0 SW 0 0.0 1 0.0 [kworker/1:1]
372 2 0 SW 0 0.0 0 0.0 [khubd]
4 2 0 SW 0 0.0 0 0.0 [kworker/0:0]
1356 2 0 SW 0 0.0 0 0.0 [kworker/0:3]
6 2 0 SW 0 0.0 0 0.0 [kworker/u:0]
9 2 0 SW 0 0.0 0 0.0 [rcu_preempt]
16 2 0 RW 0 0.0 2 0.0 [ksoftirqd/2]
1324 2 0 SW 0 0.0 0 0.0 [mmcqd/0]
35 2 0 SW 0 0.0 2 0.0 [kworker/2:1]
14 2 0 SW 0 0.0 1 0.0 [kworker/1:0]
37 2 0 SW 0 0.0 3 0.0 [kworker/3:1]
1385 2 0 SW 0 0.0 0 0.0 [jbd2/mmcblk1p3-]
1411 2 0 SW 0 0.0 0 0.0 [flush⑴79:0]
8 2 0 SW 0 0.0 0 0.0 [migration/0]
26 2 0 SW 0 0.0 1 0.0 [kdevtmpfs]
2 0 0 SW 0 0.0 0 0.0 [kthreadd]