From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tristan <9p-st@imu.li> To: 9fans@9fans.net Content-Type: text/plain; charset=UTF-8 Message-Id: <2579b8.491be6b4.43V1.mx@tumtum.plumbweb.net> In-Reply-To: References: Date: Mon, 5 Mar 2012 19:01:42 -0500 User-Agent: mx-alpha Content-Transfer-Encoding: quoted-printable Subject: Re: [9fans] usb slowness Topicbox-Message-UUID: 66a9aab0-ead7-11e9-9d60-3106f5b1d025 > 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 --=20 All original matter is hereby placed immediately under the public domain.