Date: Mon, 24 Apr 2000 15:13:35 -0500 From: "Kevin M. Dulzo" <kdulzo@caffeine.gerp.org> To: Jim King <king@sstar.com> Subject: Re: sio interrupt handler problem Message-ID: <20000424151335.A10431@caffeine.gerp.org> In-Reply-To: <003801bfae25$39a6d100$a44b8486@jking>; from king@sstar.com on Mon, Apr 24, 2000 at 02:42:09PM -0500 References: <5564.000424@pd.chel.ru><20000424114057.A692@pir.net> <14596.37283.563515.214828@localhost.nantes.kisoft-services.com> <003801bfae25$39a6d100$a44b8486@jking>
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On Mon, Apr 24, 2000 at 02:42:09PM -0500, Jim King wrote: > > One thing I've done in the past to overcome serial port problems is to patch > sys/isa/sio.c to set the FIFO receive trigger level to 8 bytes instead of 14 > (FIFO_RX_MEDH instead of FIFO_RX_HIGH). If you have a piece of hardware or > a misbehaved driver that's causing high interrupt latency this change be > really beneficial, and greatly outweighs the higher interrupt overhead when > using an 8 byte trigger. > > <soapbox> > An 8 byte trigger is a safer option that causes better operation on weird > hardware without signifcantly changing anything on good hardware. I really > wish sio.c would be changed to set the trigger to 8 bytes by default, or at > least have a flags option to change the trigger level. > </soapbox> > > Jim <hint> Couldn't something like this be turned into a tuneable nob via sysctl? </hint> Software settable UART buffering is available on MS OSes, could we not mimic this in someway? -Kevin To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-stable" in the body of the message
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