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Date: Sun, 21 Jan 2007 15:58:17 +0100 From: Willy Tarreau <w@....eu> To: Grzegorz Ja?kiewicz <gryzman@...il.com> Cc: Johannes Stezenbach <js@...uxtv.org>, Theodore Tso <tytso@....edu>, Joe Barr <joe@...rimer.com>, Linux Kernel mailing List <linux-kernel@...r.kernel.org> Subject: Re: Serial port blues On Sun, Jan 21, 2007 at 03:50:32PM +0100, Grzegorz Ja?kiewicz wrote: > funny, how even very fast box can be useless for such activities with modern > kernels, such as linux. After all, serial ports don't require too much > horsepower to be highly accurate. > >From designer perspective, I would rather go for uC solution in his case. > That is, design and build fairly simple board - based on atmega AVRs. 16mhz > 8bit chip can do so much better compared to N gigs mhz box running "modern" > operating system, these days.... It is true, but the point is not "modern" vs "ancient" OS, it's "multitasking" vs "monotasking" kernel. If your program does the busy loop, you'll get a very high accuracy at the expense of burning watts polling one bit one billion times a second waiting for a change every millisecond. 18 years ago, I wrote a soft-only 8250 emulator to connect my second 8088 to the first one's serial port at 19200 bauds. At this time, waiting for a change only took a few hundred cycles and the busy loop was the default mode of the OS anyway. Things have changed since. Willy - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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