Date: Fri, 28 Jan 2011 19:12:57 +1030 From: "Daniel O'Connor" <doconnor@gsoft.com.au> To: Hans Petter Selasky <hselasky@c2i.net> Cc: freebsd-usb@freebsd.org Subject: Re: libusb performance on 8.1 Message-ID: <2E5206C4-9327-4270-8948-FD44C62C645D@gsoft.com.au> In-Reply-To: <201101280858.05077.hselasky@c2i.net> 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>
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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
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