On Tue, Jul 23, 2013 at 10:33 AM, Stoddard, Nate (GE Healthcare) <Nate.Stoddard@xxxxxxxxxx> wrote: > Hello, > > We are attempting to create a system that will support 8 full speed USB devices each sending a 64-byte transfer every 1ms via interrupt endpoints. When we connect 5 full speed USB devices our USB host use 24% of the CPU, but when we connect a 6th device, the CPU goes to 100%. Has anyone else seen this type of CPU jump or know what could be causing it? > > Devices CPU Total Throughput > 1 7% 64 KB/s > 2 11% 128 KB/s > 3 15% 192 KB/s > 4 19% 256 KB/s > 5 24% 320 KB/s > 6 99% (should be 384 KB/s, but the iMX535 misses sending IN tokens in some SOF periods) > > We are using a Freescale iMX535 board running at 800 MHz as the USB host. One of the iMX535 EHCI root controllers is connected to a high speed USB hub which has two ports each connected to another high speed USB hub (giving us 8 ports for USB devices). Each hub has multi-TT support. The iMX535 is running Linux 2.6.35, and our test application uses Please try it on a 3.10.2 kernel and let us know the result. Regards, Fabio Estevam -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
