Date: Thu, 7 Sep 2000 21:17:14 -0700 (PDT) From: John Baldwin <jhb@pike.osd.bsdi.com> To: Bruce Evans <bde@zeta.org.au> Cc: Warner Losh <imp@village.org>, The Hermit Hacker <scrappy@hub.org>, freebsd-current@FreeBSD.ORG, freebsd-smp@FreeBSD.ORGG Subject: Re: 'interrupt-level buffer overflows' for sio device? Message-ID: <200009080417.VAA32639@pike.osd.bsdi.com> In-Reply-To: <Pine.BSF.4.21.0009081148120.30454-100000@besplex.bde.org> from Bruce Evans at "Sep 8, 2000 11:50:45 am"
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Bruce Evans wrote: > On Thu, 7 Sep 2000, Warner Losh wrote: > > > In message <Pine.BSF.4.21.0009062102140.572-100000@thelab.hub.org> The Hermit Hacker writes: > > : sio1: 32 more interrupt-level buffer overflows (total 32) > > > > >From the man page: > > sio%d: interrupt-level buffer overflow. Problem in the bottom half of > > the driver. > > > > This likely means that the bottom half of sio isn't running fast > > enough to harvest the characters in the interrupt level buffers. > > This means that fast interrupt handlers aren't actually fast. Especially > if it occurs for slow devices like mouses. Even slow interrupt handlers > had about 10 times lower latency than necessary for 1200 bps serial mouses. > > Bruce Well unfortunately this doesn't make sense since the sio interrupt _is_ still fast, and thus is not run as a thread as other interrupts, but is run just like old fast interrupts were. However, there is an issue with sio right now in that it's not getting any input (actually, on my test machines, I can't get the stupid hardware to set the actual DCD bit, so I can't even open the devices *sigh*). My guess then is that we aren't scheduling the soft interrupt to harvest the data in the top half from the bottom half. -- John Baldwin <jhb@bsdi.com> -- http://www.FreeBSD.org/~jhb/ PGP Key: http://www.cslab.vt.edu/~jobaldwi/pgpkey.asc "Power Users Use the Power to Serve!" - http://www.FreeBSD.org/ To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message
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