Date: Fri, 24 Jul 2009 07:47:45 -0400 From: John Baldwin <jhb@freebsd.org> To: Alexander Best <alexbestms@math.uni-muenster.de> Cc: Alexey Shuvaev <shuvaev@physik.uni-wuerzburg.de>, freebsd-hackers@freebsd.org Subject: Re: checking number of parallel ports installed and their port adresses Message-ID: <200907240747.45738.jhb@freebsd.org> In-Reply-To: <permail-20090724104234f0889e8400006fa9-a_best01@message-id.uni-muenster.de> References: <permail-20090724104234f0889e8400006fa9-a_best01@message-id.uni-muenster.de>
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On Friday 24 July 2009 6:42:34 am Alexander Best wrote: > thanks for the hint. > > if spent a bit of time and turned the in/out opcodes to ppi ioctls. actually i > was very surprised about the results since you said the overhead wouldn't be > that big. > > uploading a 256 kbyte file i got the following results: > > using ppi: 17.120 seconds > using in/out opcodes: 8.001 seconds > > so i think i'll rather stick to my old inline assembly code even if it can't > be considered nice programming style, but the ppi overhead isn't something i > can cope with in my app. Hmmm, that is a bit much. Though I do suppose you are incurring a user -> kernel -> user transition for each I/O access. -- John Baldwin
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