Date: Mon, 24 Apr 2000 16:03:53 -0500 From: "Jim King" <king@sstar.com> To: "Kevin M. Dulzo" <kdulzo@caffeine.gerp.org>, <freebsd-stable@freebsd.org> Subject: Re: sio interrupt handler problem Message-ID: <006901bfae30$9f74d300$a44b8486@jking> References: <5564.000424@pd.chel.ru><20000424114057.A692@pir.net> <14596.37283.563515.214828@localhost.nantes.kisoft-services.com> <003801bfae25$39a6d100$a44b8486@jking> <20000424151335.A10431@caffeine.gerp.org>
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On Monday, April 24, 2000 3:13 PM, Kevin M. Dulzo wrote: > 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 Sounds like a good idea to me. Jim To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-stable" in the body of the message
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