From owner-freebsd-usb@FreeBSD.ORG Fri Jan 28 08:43:08 2011 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 D6B69106564A for ; Fri, 28 Jan 2011 08:43:08 +0000 (UTC) (envelope-from doconnor@gsoft.com.au) Received: from cain.gsoft.com.au (cain.gsoft.com.au [203.31.81.10]) by mx1.freebsd.org (Postfix) with ESMTP id 5B1BD8FC15 for ; Fri, 28 Jan 2011 08:43:07 +0000 (UTC) Received: from ur.dons.net.au (ppp203-122-198-244.lns6.adl6.internode.on.net [203.122.198.244]) (authenticated bits=0) by cain.gsoft.com.au (8.14.4/8.14.3) with ESMTP id p0S8gvMt030885 (version=TLSv1/SSLv3 cipher=AES128-SHA bits=128 verify=NO); Fri, 28 Jan 2011 19:12:58 +1030 (CST) (envelope-from doconnor@gsoft.com.au) Mime-Version: 1.0 (Apple Message framework v1082) Content-Type: text/plain; charset=us-ascii From: "Daniel O'Connor" In-Reply-To: <201101280858.05077.hselasky@c2i.net> Date: Fri, 28 Jan 2011 19:12:57 +1030 Content-Transfer-Encoding: quoted-printable Message-Id: <2E5206C4-9327-4270-8948-FD44C62C645D@gsoft.com.au> References: <9CF6C32F-E230-446B-94FC-C57F0F02B0E4@gsoft.com.au> <201101221433.23194.hselasky@c2i.net> <6AD22899-0B00-483D-A01E-786029A82C9F@gsoft.com.au> <201101280858.05077.hselasky@c2i.net> To: Hans Petter Selasky X-Mailer: Apple Mail (2.1082) X-Spam-Score: 0.163 () BAYES_00,RDNS_DYNAMIC X-Scanned-By: MIMEDefang 2.67 on 203.31.81.10 Cc: freebsd-usb@freebsd.org Subject: Re: libusb performance on 8.1 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: Fri, 28 Jan 2011 08:43:08 -0000 On 28/01/2011, at 18:28, Hans Petter Selasky wrote: > For this kind of applications ISOCHRONOUS transfers should be used. = Then you=20 > can have a double buffer guard in the range 1-56ms, regardless of the = buffer=20 > size the hardware uses. Hmm, OK, I will have a look at changing it, although it is a bit of a = pain because you can't stall an ISO EP and I'm using stall to indicate = an error. Is it possible to change the amount that is buffered? This is a = specialised application so a custom kernel is no problem. Even a hint in = the right direction would be greatly appreciated :) > You could also try an XHCI controller, because the BULK buffering is = done=20 > differently there. OK thanks, I'll try that too. >=20 >> I obviously don't need any more >> throughput, however my application is very sensitive to latency, as I = am >> reading out of a fairly small FIFO and if it fills up my entire run = has to >> be aborted. >=20 >=20 >=20 > --HPS >=20 -- Daniel O'Connor software and network engineer for Genesis Software - http://www.gsoft.com.au "The nice thing about standards is that there are so many of them to choose from." -- Andrew Tanenbaum GPG Fingerprint - 5596 B766 97C0 0E94 4347 295E E593 DC20 7B3F CE8C