From owner-freebsd-usb@FreeBSD.ORG Wed Mar 4 08:59:18 2009 Return-Path: Delivered-To: freebsd-usb@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 71719106566C for ; Wed, 4 Mar 2009 08:59:18 +0000 (UTC) (envelope-from hselasky@c2i.net) Received: from swip.net (mailfe14.tele2.se [212.247.155.161]) by mx1.freebsd.org (Postfix) with ESMTP id D05768FC16 for ; Wed, 4 Mar 2009 08:59:17 +0000 (UTC) (envelope-from hselasky@c2i.net) X-Cloudmark-Score: 0.000000 [] X-Cloudmark-Analysis: v=1.0 c=1 a=Ma5krZdYoiIA:10 a=-DXRHlJb_54A:10 a=F9Ddb8ZnJZvc46m2WQEPHQ==:17 a=8kQB0OdkAAAA:8 a=4TiyodsbXAEmuLSezzYA:9 a=Z05caA5rYOklySfM2wkA:7 a=yuabBorXCFmh_gcKruEvH5gkcSoA:4 a=LY0hPdMaydYA:10 a=9aOQ2cSd83gA:10 Received: from [85.19.79.136] (account mc467741@c2i.net HELO laptop.bitfrost.local) by mailfe14.swip.net (CommuniGate Pro SMTP 5.2.6) with ESMTPA id 461703500; Wed, 04 Mar 2009 09:59:16 +0100 From: Hans Petter Selasky To: "M. Warner Losh" Date: Wed, 4 Mar 2009 10:01:36 +0100 User-Agent: KMail/1.9.7 References: <200903032243.31914.hselasky@c2i.net> <200903040922.48163.hselasky@c2i.net> <20090304.014655.1820405796.imp@bsdimp.com> In-Reply-To: <20090304.014655.1820405796.imp@bsdimp.com> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200903041001.37376.hselasky@c2i.net> Cc: freebsd-usb@freebsd.org Subject: Re: Low perfomance when read from usb flash drive X-BeenThere: freebsd-usb@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: FreeBSD support for USB List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 04 Mar 2009 08:59:18 -0000 On Wednesday 04 March 2009, M. Warner Losh wrote: > In message: <200903040922.48163.hselasky@c2i.net> > > Hans Petter Selasky writes: > : Hi Steve, > : > : On Tuesday 03 March 2009, Steve Calfee wrote: > : > > I think the reduced performance can be explained by a clamp on the > : > > interrupt rate around 1000 interrupts per second instead of 8000. > : > > Maybe someone has an explanation for this? > : > > > : > > The EHCI is being programmed to interrupt at 125us intervals, but > : > > there seems to be limits other places. > : > > > : > > It is possible to workaround this in the umass driver by doing the > : > > cmd + read in one operation. > : > > : > Hi Hans, > : > > : > I am looking at using FreeBSD in an embedded product. I have not > : > examined your ehci software, but I am aware of how Linux and other > : > OSes run the controller. > : > > : > Why are you taking an interrupt every uFrame SOF? > : > : If the transaction completes before 125us we take the interrupt before > : 125us. The problem is that the interrupt delay becomes critical to > : performance when the interrupt rate is close to the interrupt limitation. > : > : For example: > : > : Transferring 13Mbyte/sec at blocksize equal to 65536 bytes generates 600 > : interrupts. Hence the Mass Storage state machine has three steps the > : throughput is computed like (600/3)*65536 bytes. If we on the average > : have to wait 0.5ms for an interrupt we loose throughput. > > Shouldn't you be using filters and such to make this less relevant? A > filter runs on the order of 5us after the interrupt on fast machines, > and 20us on slower (400MHz) ones. You can feed the pipeline better, > and handle higher interrupt rates... > Yes, that's one possibility. It looks like there is some timing slightly out of sync. I have an AMD box with the same symptoms. I will try to figure out what is causing it. --HPS