Re: [9fans] usb slowness

[Tristan <9p-st@imu.li>]

> You can use time(1) while reading usb disk to see if cpu is really the
> bottleneck, or if in fact your machine is spending most of its time
> waiting for a usb interrupt.  If the machine is mostly idle, profiling
> clock ticks should usually find it sitting at the HLT instruction which
> happens to be couple of bytes before _strayintr.

time suggests that it is waiting for interrupts: 0.03u 0.75s 25.42r
if i force polling, it's a little faster: 0.01u 0.45s 17.70r
(dd -if /dev/sdU0.0/data -of /dev/null -bs 65536 -count 1024)

holding a second, time wouldn't show interrupt-handling time, correct?

load remains fairly low during both, but system calls and context
switches are high.

time to read up on ehci...

thank you,
tristan

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