[AT&T Samsung Galaxy S II SGH-I777] elherr:
CM9 USB storage performance?

I was taking a look at write transfer speeds to Sandisk class 4 micro SD both in I777 and in USB reader. I777/CM9 USB storage speeds were not exactly stellar compared to USB SD reader, with fairly large intervals with no data being transferred. I did not benchmark this on stock i777 firmware. Is this a CM9 issue or inherent to I777 hardware?

I'm currently running CM9 0513.

In phone USB storage write performance (Debian Linux 'dstat' output):

----total-cpu-usage---- -dsk/total- -net/total- ---paging-- ---system--
usr sys idl wai hiq siq| read writ| recv send| in out | int csw
5 2 90 3 0 0| 109k 24k| 0 0 | 0 0 | 240 463
3 1 0 96 0 0| 0 12k| 0 0 | 0 0 | 273 456
6 9 0 85 0 0|7268k 120k| 0 0 | 0 0 |1182 2720
3 1 0 96 0 0| 0 0 | 0 0 | 0 0 | 206 395
2 1 0 97 0 0| 0 68k| 84B 0 | 0 0 | 195 438
2 2 0 95 0 1| 0 4080k| 42B 0 | 0 0 | 348 744
2 2 0 96 0 0| 0 276k| 0 0 | 0 0 | 224 463
5 6 0 89 0 0|4928k 4059k| 0 0 | 0 0 | 981 2144
2 1 0 97 0 0| 0 4200k| 0 0 | 0 0 | 409 828
6 6 0 88 0 0|5920k 44k| 0 0 | 0 0 | 893 2045
2 2 0 96 0 0| 0 0 | 0 0 | 0 0 | 152 367
1 1 0 98 0 0| 0 0 | 0 0 | 0 0 | 113 305
2 1 0 97 0 0| 0 0 | 0 0 | 0 0 | 126 324
2 1 0 97 0 0| 0 0 | 0 0 | 0 0 | 129 343

1 1 0 98 0 0| 0 0 | 0 0 | 0 0 | 238 314
19 7 0 73 0 0|6308k 4096k| 0 0 | 0 0 |1351 2894
9 4 0 87 0 0| 128k 4170k| 0 0 | 0 0 |1203 1172
6 2 0 92 0 0| 0 0 | 0 0 | 0 0 | 990 775
8 11 0 80 0 1| 11M 4090k| 0 0 | 0 0 |2266 3881
3 6 0 91 0 0|1916k 0 | 0 0 | 0 0 | 565 1141
4 9 0 87 0 0| 0 4096k| 0 0 | 0 0 | 530 737
5 8 0 87 0 0| 0 0 | 132B 336B| 0 0 | 354 614

USB SD reader:

----total-cpu-usage---- -dsk/total- -net/total- ---paging-- ---system--
usr sys idl wai hiq siq| read writ| recv send| in out | int csw
7 12 0 80 0 1|5644k 4105k| 0 0 | 0 0 | 810 1325
5 8 0 87 0 0| 0 1440k| 0 0 | 0 0 | 407 622
6 9 0 85 0 0| 36k 2616k| 0 0 | 0 0 | 648 1071
7 11 0 82 0 0| 18M 2400k| 0 0 | 0 0 | 822 1246
4 3 0 92 0 1| 0 2897k| 0 0 | 0 0 | 382 703
5 3 0 92 0 0| 0 3019k| 0 0 | 0 0 | 418 672
5 3 0 92 0 0| 0 2660k| 0 0 | 0 0 | 407 757
4 2 0 94 0 0| 0 912k| 0 0 | 0 0 | 268 504
3 4 0 93 0 0| 0 3322k| 0 0 | 0 0 | 411 798
4 2 0 94 0 0| 0 1440k| 0 0 | 0 0 | 340 648
7 8 0 84 0 1|9112k 2646k| 500B 439B| 0 0 | 760 1279
6 5 0 89 0 0| 0 2760k| 445B 321B| 0 0 | 589 1027
6 3 0 90 0 1| 0 2360k| 0 0 | 0 0 | 486 896
4 3 0 93 0 0| 0 704k| 0 0 | 0 0 | 276 552
4 3 0 93 0 0| 0 1440k| 0 0 | 0 0 | 337 633
5 6 0 89 0 0|9560k 2704k| 0 0 | 0 0 | 600 915
5 4 0 90 0 1| 0 2833k| 0 0 | 0 0 | 461 784
5 4 0 91 0 0|1728k 2164k| 42B 0 | 0 0 | 416 733
4 5 0 91 0 0|4928k 4320k| 42B 0 | 0 0 | 597 1069
6 7 0 86 0 1|6544k 2873k| 42B 0 | 0 0 | 599 1026
4 3 0 93 0 0| 0 1800k| 0 0 | 0 0 | 395 691
6 5 0 89 0 0|6388k 3840k| 0 0 | 0 0 | 595 1020
3 4 0 93 0 0| 0 4406k| 0 0 | 0 0 | 512 925
6 6 0 88 0 0|5400k 4932k| 0 0 | 0 0 | 616 1091
6 6 0 87 0 1|6832k 4733k| 0 0 | 0 0 | 687 1133
6 6 0 88 0 0|3776k 4381k| 0 0 | 0 0 | 625 1028
4 5 0 91 0 0|5204k 4440k| 0 0 | 0 0 | 600 1031
3 3 0 93 0 1| 0 4230k| 0 0 | 0 0 | 458 777
7 8 0 85 0 0|8136k 4451k| 183B 201B| 0 0 | 693 1274
8 5 0 86 0 1| 0 4309k| 878B 559B| 0 0 | 654 1228
7 8 0 85 0 0|6204k 4440k| 99B 84B| 0 0 | 766 1266
5 8 0 86 0 1|6236k 3947k| 0 0 | 0 0 | 689 1132