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Date:      Sun, 24 Sep 2000 11:30:08 -0700
From:      Alfred Perlstein <bright@wintelcom.net>
To:        Dag-Erling Smorgrav <des@ofug.org>
Cc:        Warner Losh <imp@village.org>, The Hermit Hacker <scrappy@hub.org>, Bruce Evans <bde@zeta.org.au>, freebsd-current@FreeBSD.ORG, freebsd-smp@FreeBSD.ORG
Subject:   Re: 'interrupt-level buffer overflows' for sio device?
Message-ID:  <20000924113008.N9141@fw.wintelcom.net>
In-Reply-To: <xzp7l817ij1.fsf@flood.ping.uio.no>; from des@ofug.org on Sun, Sep 24, 2000 at 08:26:58PM %2B0200
References:  <Pine.BSF.4.21.0009080008090.527-100000@thelab.hub.org> <200009080314.VAA50701@harmony.village.org> <xzp7l817ij1.fsf@flood.ping.uio.no>

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* Dag-Erling Smorgrav <des@ofug.org> [000924 11:27] wrote:
> Warner Losh <imp@village.org> writes:
> > In message <Pine.BSF.4.21.0009080008090.527-100000@thelab.hub.org> The Hermit Hacker writes:
> > : Okay, I'm a little confused here ... from what I'm reading/following, this
> > : isn't a new problem ... or is it?  If not, why has it suddenly manifested
> > : itself with the new SMP code?
> > It seems to be new with the SMP code.  At least that's what my reading
> > of the original message is.
> 
> I'm seeing the same thing as Marc, but I have a little more info:
> 
> 1) it started after the SMPng commit.
> 
> 2) it's not just sio, it's everything:
> 
>     - interactive response is markedly slower.
> 
>     - the keyboard autorepeats slower than it used to (even with
>       kbdcontrol -r fast).
> 
>     - I/O bound processes such as mpg123 or cvsup will pause briefly
>       when there is other I/O going on (moving the mouse, typing fast,
>       holding down a key on the keyboard), which they didn't use to.

This is basically a result of the entire kernel running at the
equivelant of splhigh, all interrupts are blocked until a context
switch in kernel land.

There's work in progress to mpsafe the drivers (at least for
ethernet, more will arrive later).

-- 
-Alfred Perlstein - [bright@wintelcom.net|alfred@freebsd.org]
"I have the heart of a child; I keep it in a jar on my desk."


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