Try the following patch. Look for a line in /sys/i386/isa/sio.c that looks like:
com->fifo_image = t->c_ospeed <= 4800 ? FIFO_ENABLE : FIFO_ENABLE | FIFO_RX_HIGH; Replace FIFO_RX_HIGH with FIFO_RX_MEDH, and if that doesn't work try FIFO_RX_MEDL instead. This patch changes the RX FIFO trigger point from 12 down to 8 (or 4). With it set to 12 the system only has 4 character periods to respond to the IRQ. Normally a Pentium or higher should be able to handle this, however things like SMP or non-DMA mode for your harddisk may hold off interrupts for longer than normal. With it set to 8 there is twice as long to process the IRQ before an overflow occurs. Actually the sio driver should really detect silo overflows and drop the FIFO level a notch automatically. Hmm, if I have some free time I might look into it. The bad side is that this patch increases the IRQ load on the box. Although for a Pentium the serial processing load is a fraction of a percent so double that is still negligable. Cheers. In nlc.lists.freebsd-current you wrote: > I didn't get a response from the questions list, so let's try here. > I've been getting my server ready to switch from FreeBSD 2.2.2 to 3.0 > Release. Everything was going well until I tried to bring my kernel ppp > link up to my isp. I get many silo overflow messages when there's any > activity on the line. The connection doesn't seem very responsive either. > This machine is a dual pentium pro. I've built an smp kernel which seems > to work fine otherwise. I've arranged to build the new system on another > disk so I can easily switch between the 2.2.2 system and the 3.0 system. > Everything works fine with 2.2.2. I've seen many messages in the archive > about silo overflows, but there doesn't seem to be a real solution in > them. Is this ever likely to work or should I just wait for 3.1? > Steve Rose > To Unsubscribe: send mail to majord...@freebsd.org > with "unsubscribe freebsd-current" in the body of the message -- -- +------------------------------------------------------------+ . | John Saunders - mailto:j...@nlc.net.au (EMail) | ,--_|\ | - http://www.nlc.net.au/ (WWW) | / Oz \ | - 02-9489-4932 or 041-822-3814 (Phone) | \_,--\_/ | NHJ NORTHLINK COMMUNICATIONS - Supplying a professional, | v | and above all friendly, internet connection service. | +------------------------------------------------------------+ To Unsubscribe: send mail to majord...@freebsd.org with "unsubscribe freebsd-current" in the body of the message