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77 wiersze
4.0 KiB
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<!-- received="Wed Jun 30 03:02:38 1999 PDT" -->
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<!-- sent="Wed, 30 Jun 1999 11:47:26 +0200" -->
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<!-- name="abel deuring" -->
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<!-- email="a.deuring@satzbau-gmbh.de" -->
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<!-- subject="Re: problems increasing SG_BIG_BUFF" -->
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<!-- inreplyto="problems increasing SG_BIG_BUFF" -->
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<title>sane-devel: Re: problems increasing SG_BIG_BUFF</title>
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<h1>Re: problems increasing SG_BIG_BUFF</h1>
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<b>abel deuring</b> (<a href="mailto:a.deuring@satzbau-gmbh.de"><i>a.deuring@satzbau-gmbh.de</i></a>)<br>
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<i>Wed, 30 Jun 1999 11:47:26 +0200</i>
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<p>
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<ul>
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<li> <b>Messages sorted by:</b> <a href="date.html#246">[ date ]</a><a href="index.html#246">[ thread ]</a><a href="subject.html#246">[ subject ]</a><a href="author.html#246">[ author ]</a>
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<li> <b>Next message:</b> <a href="0247.html">Douglas Gilbert: "Re: Problem with snapscan, aha1505, linux kernel 2.2.9"</a>
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<li> <b>Previous message:</b> <a href="0245.html">Francois Desarmenien: "Re: Problem with snapscan, aha1505, linux kernel 2.2.9"</a>
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<li> <b>Maybe in reply to:</b> <a href="0047.html">Andreas Buesching: "problems increasing SG_BIG_BUFF"</a>
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<!-- nextthread="start" -->
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<li> <b>Next in thread:</b> <a href="0248.html">Douglas Gilbert: "Re: problems increasing SG_BIG_BUFF"</a>
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</ul>
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Hi all!<br>
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<p>
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Rainer Krienke wrote:<br>
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<p>
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<i>> Before I used the old sg driver with a patch that uses a static buffer</i><br>
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<i>> of 1MBytes in size. This prevents the sg driver of beeing used as a</i><br>
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<i>> module but has a really great effect in scanning time. To scan a DINA4</i><br>
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<i>> page in 300 DPI color mode then takes only 45 seconds. Compared to the</i><br>
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<i>> new sg driver this is about 4 times faster and after all it probably</i><br>
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<i>> will be good for the scanner hardware itself as well (it needs do to</i><br>
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<i>> backtracking only about 5 times compared to >20 times using the new</i><br>
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<i>> driver).</i><br>
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<i>> </i><br>
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<i>> Wouldn´t it be possible to include such a static buffer (optional) in</i><br>
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<i>> the new sg driver as well? The best new driver doesn't help, if you</i><br>
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<i>> actually cannot use it in real live and as you can see from the examples</i><br>
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<i>> avove this is true for the current situation.</i><br>
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<p>
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While I have never thought much about internals of kernel programming, I<br>
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think that there should be better ways to avoid scanner carriage stops<br>
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than to increase the size of an SG-buffer. <br>
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<p>
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sanei_scsi.c has already "its part" of an implementation of asynchronous<br>
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SCSI commands (sanei_scsi_req_enter and sanei_scsi_req_wait); and even<br>
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while their Linux implementation is only a "fake", the use of these<br>
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functions reduced the number of carriage stops with the Sharp JX250<br>
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scanner dramatically. <br>
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<p>
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This suggests that most if not all scanner carriage stops can be avoided<br>
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if consecutive reads commands are sent to the scanner as soon as<br>
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possible after the data from the previous command has been read in.<br>
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<p>
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Doug, what do you think about adding ioctl-calls to the SG driver which<br>
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implement queueing of asynchrounous SCSI commands? <br>
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<p>
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Abel<br>
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<p>
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<pre>
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--
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Source code, list archive, and docs: <a href="http://www.mostang.com/sane/">http://www.mostang.com/sane/</a>
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</pre>
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<!-- body="end" -->
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<p>
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<ul>
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<!-- next="start" -->
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<li> <b>Next message:</b> <a href="0247.html">Douglas Gilbert: "Re: Problem with snapscan, aha1505, linux kernel 2.2.9"</a>
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<li> <b>Previous message:</b> <a href="0245.html">Francois Desarmenien: "Re: Problem with snapscan, aha1505, linux kernel 2.2.9"</a>
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<li> <b>Maybe in reply to:</b> <a href="0047.html">Andreas Buesching: "problems increasing SG_BIG_BUFF"</a>
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<!-- nextthread="start" -->
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<li> <b>Next in thread:</b> <a href="0248.html">Douglas Gilbert: "Re: problems increasing SG_BIG_BUFF"</a>
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<!-- reply="end" -->
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</ul>
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