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Date:      Tue, 13 Aug 2002 05:25:21 +1000 (EST)
From:      Bruce Evans <bde@zeta.org.au>
To:        Maksim Yevmenkin <myevmenk@exodus.net>
Cc:        Maksim Yevmenkin <Maksim.Yevmenkin@exodus.net>, <current@FreeBSD.ORG>
Subject:   Re: Interrupt vs. polling on -current
Message-ID:  <20020813051700.M25922-100000@gamplex.bde.org>
In-Reply-To: <3D57EFDB.94242A71@exodus.net>

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On Mon, 12 Aug 2002, Maksim Yevmenkin wrote:

> Bruce Evans wrote:
> >
> > On Sun, 11 Aug 2002, Maksim Yevmenkin wrote:
> [...]
>
> > > BTW, i see "silo overflow" messages when i run ppp via null-modem
> > > cable. in this configuration i'm using serial port 0 which is on
> > > board and hase irq 4 with fast interrupts.
> >
> > What else is active when you get these?
>
> not much: X, user space ppp and i'm doing moderate size transfers
> via ftp between my current laptop and FreeBSD 4.5 desktop. i also
> see these errors while cvsup'ing my -current laptop.

Some graphics cards can cause sio problems, by using too bus cycles so
that sio doesn't get even an average of about 5 i/o cycles per character
time that it needs to function.  5 might sound like not many, but it is
5 isa cycles so it takes 6 usec every 87 usec at 115200 bps.  20 devices
wanting that much of the bus just won't work.

Bruce


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