为什么驱动中CTL phase浪费巨长时间？

我做一个USB的东东，用bushound测了一下发现，驱动中CTL phase浪费巨长时间，
平均在500ms左右，而传4096Bytes数据才50ms。CTL有什么用?


bus Hound检测如下：

Device Phase Data Description Time Cmd.Phase.Ofs(rep)
------ ----- ------------------------- ---------------- ----- ------------------
7.0 CTL c0 01 00 40 - 00 00 00 00 VENDOR 269ms 1.1.0
7 STAK 0f 00 00 e0 - 70 4d 5f c1 INTERNAL IOCTL 56us 1.2.0
7 URB 50 00 08 00 - 00 00 00 00 CONTROL TRANSFER 3.0ms 1.3.0
7 STAK 0f 00 00 e0 - 00 7a 5f c1 INTERNAL IOCTL 342us 2.1.0
7 USTS 00 09 00 80 short transfer 1.6ms 2.2.0
7 URB 48 00 09 00 - 00 09 00 80 BULK/INT XFER 27us 2.3.0
7 STAK 0f 00 00 e0 - 00 7a 5f c1 INTERNAL IOCTL 280us 3.1.0
7 LEN 00 10 00 00 4096 51ms 3.2.0
7 DI 70 80 70 80 - 72 80 0c fa p.p.r... 53us 3.3.0
7 URB 48 00 09 00 - 00 00 00 00 BULK/INT XFER 21us 3.4.0
7 STAK 0f 00 00 e0 - 00 7a 5f c1 INTERNAL IOCTL 14ms 4.1.0
7 LEN 00 10 00 00 4096 42ms 4.2.0
7 DI 3e 81 3f 81 - 42 81 0c fa >.?.B... 54us 4.3.0
7 URB 48 00 09 00 - 00 00 00 00 BULK/INT XFER 45us 4.4.0
7.0 CTL c0 01 00 40 - 00 00 00 00 VENDOR 518ms 5.1.0
7 STAK 0f 00 00 e0 - 70 4d 5f c1 INTERNAL IOCTL 101us 5.2.0
7 URB 50 00 08 00 - 00 00 00 00 CONTROL TRANSFER 2.9ms 5.3.0
7 STAK 0f 00 00 e0 - 00 7a 5f c1 INTERNAL IOCTL 300us 6.1.0
7 USTS 00 09 00 80 short transfer 1.7ms 6.2.0
7 URB 48 00 09 00 - 00 09 00 80 BULK/INT XFER 23us 6.3.0
7 STAK 0f 00 00 e0 - 00 7a 5f c1 INTERNAL IOCTL 293us 7.1.0
7 LEN 00 10 00 00 4096 51ms 7.2.0
7 DI 46 81 47 81 - 4a 81 0c fa F.G.J... 51us 7.3.0
7 URB 48 00 09 00 - 00 00 00 00 BULK/INT XFER 20us 7.4.0
7 STAK 0f 00 00 e0 - 00 7a 5f c1 INTERNAL IOCTL 13ms 8.1.0
7 LEN 00 10 00 00 4096 41ms 8.2.0
7 DI 15 82 15 82 - 19 82 0d fa ........ 30us 8.3.0
7 URB 48 00 09 00 - 00 00 00 00 BULK/INT XFER 36us 8.4.0
7.0 CTL c0 01 00 40 - 00 00 00 00 VENDOR 516ms 9.1.0
7 STAK 0f 00 00 e0 - 70 4d 5f c1 INTERNAL IOCTL 54us 9.2.0
7 URB 50 00 08 00 - 00 00 00 00 CONTROL TRANSFER 3.0ms 9.3.0
7 STAK 0f 00 00 e0 - 00 7a 5f c1 INTERNAL IOCTL 311us 10.1.0
7 USTS 00 09 00 80 short transfer 1.6ms 10.2.0
7 URB 48 00 09 00 - 00 09 00 80 BULK/INT XFER 25us 10.3.0
7 STAK 0f 00 00 e0 - 00 7a 5f c1 INTERNAL IOCTL 250us 11.1.0
7 LEN 00 10 00 00 4096 51ms 11.2.0
7 DI 1d 82 1d 82 - 21 82 0d fa ....!... 42us 11.3.0
7 URB 48 00 09 00 - 00 00 00 00 BULK/INT XFER 19us 11.4.0
7 STAK 0f 00 00 e0 - 00 7a 5f c1 INTERNAL IOCTL 13ms 12.1.0
7 LEN 00 10 00 00 4096 42ms 12.2.0
7 DI 7f 7f 7f 7f - 7f 7f 7f 7f ........ 31us 12.3.0
7 URB 48 00 09 00 - 00 00 00 00 BULK/INT XFER 39us 12.4.0
7.0 CTL c0 01 00 40 - 00 00 00 00 VENDOR 530ms 13.1.0
7 STAK 0f 00 00 e0 - 70 4d 5f c1 INTERNAL IOCTL 100us 13.2.0
7 URB 50 00 08 00 - 00 00 00 00 CONTROL TRANSFER 2.9ms 13.3.0
7 STAK 0f 00 00 e0 - 00 7a 5f c1 INTERNAL IOCTL 352us 14.1.0
7 USTS 00 09 00 80 short transfer 1.6ms 14.2.0
7 URB 48 00 09 00 - 00 09 00 80 BULK/INT XFER 28us 14.3.0
7 STAK 0f 00 00 e0 - 00 7a 5f c1 INTERNAL IOCTL 262us 15.1.0
7 LEN 00 10 00 00 4096 51ms 15.2.0
7 DI 74 82 74 82 - 78 82 0d fa t.t.x... 41us 15.3.0
7 URB 48 00 09 00 - 00 00 00 00 BULK/INT XFER 21us 15.4.0
7 STAK 0f 00 00 e0 - 00 7a 5f c1 INTERNAL IOCTL 13ms 16.1.0
7 LEN 00 10 00 00 4096 42ms 16.2.0
7 DI 7f 7f 7f 7f - 7f 7f 7f 7f ........ 54us 16.3.0
7 URB 48 00 09 00 - 00 00 00 00 BULK/INT XFER 41us 16.4.0

control transfer本身的速度就很慢，它的目的就不是给告诉传输用的。这应该是物理因素决定的。

可是也太长了，500多ms,要几十ms还可以理解。

control transfer本身的速度就很慢，它的目的就不是给告诉传输用的。这应该是物理因素决定的。