Date: Thu, 8 Jun 1995 01:26:45 +1000 (EST) From: michael butler <imb@scgt.oz.au> To: jleppek@suw2k.ess.harris.com (James Leppek) Cc: freebsd-hackers@freefall.cdrom.com Subject: Re: silo overflows Message-ID: <199506071526.BAA13001@asstdc.scgt.oz.au> In-Reply-To: <9506071209.AA20749@borg.ess.harris.com> from "James Leppek" at Jun 7, 95 08:09:08 am
next in thread | previous in thread | raw e-mail | index | archive | help
James Leppek writes: > Thanks for the info. > The only bus hogging DMA I could think of is the 1542CF but it is > at the default settings which I thought were safe. In the interest of disk performance, FreeBSD uses bus-on/bus-off times which are quite aggressive (11/4uS ?) as compared to, say, Interactive at about 9 and 6uS. As I understand it, heavy disk work, therefore, only yields 4uS of CPU time (to service the serial port(s)) before grabbing another 11uS for disk transfers .. probably not including bus-request and acknowledge latencies. > Is there a "cleaner" way to adjust the fifo trigger levels than making > another constant like FIFO_TRIGGER_10? perhaps a sysctl or stty option? You only have four options .. 1, 4, 8 or 14 .. Bruce's suggestion will afford that flexibility in a later version without necessitating kernel recompilation to "tune" a workable result, michael
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?199506071526.BAA13001>