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Date:      Wed, 16 Jun 2004 04:41:50 -0600
From:      Scott Long <scottl@freebsd.org>
To:        yongari@kt-is.co.kr
Cc:        freebsd-sparc64@freebsd.org
Subject:   Re: IT! WORKS!
Message-ID:  <40D023EE.7020302@freebsd.org>
In-Reply-To: <20040616102504.GB8881@kt-is.co.kr>
References:  <40CFC0A0.1000604@mWare.ca> <20040616034055.GE26532@electra.cse.Buffalo.EDU> <40CFC2CF.8080509@mWare.ca> <20040616085518.GA8881@kt-is.co.kr> <40D011A8.1030404@freebsd.org> <20040616102504.GB8881@kt-is.co.kr>

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Pyun YongHyeon wrote:
> On Wed, Jun 16, 2004 at 03:23:52AM -0600, Scott Long wrote:
>  > Pyun YongHyeon wrote:
>  > >On Tue, Jun 15, 2004 at 11:47:27PM -0400, Mykel wrote:
>  > > > Ken Smith wrote:
>  > >...
>  > > > 
>  > > > Now how about the console? how can I make typing at least practical on 
>  > > > here? I was hoping to use this as a desktop machine.
>  > > > 
>  > >
>  > >Because I got big trouble while testing TCP/UDP cksum offload
>  > >fix for hme(4) on console, I touched ofw_console code. I stole
>  > >the code from OpenBSD. It seems that now the console works as
>  > >expected. No more 1 sec. pause needed to see correct typing on
>  > >keyboard. Here is patch. I'm not familiar with tty code, so
>  > >it may be just dirty hack or it may not work except my Ultra2.
>  > >
>  > >Regards,
>  > >Pyun YongHyeon
>  > >
>  > 
>  > Another nice patch =-)   The only question that I have is, is it 
>  > possible to have more than OFBURSTLEN characters in the outq, and
>  > if so, what happens to the extra charaters?  Do they just stay in
>  > the outq until the next poll cycle?  I guess that it's hard to
> I'm sorry I don't know. I just thought OF_write() is too slow,
> it would be more efficient to write at once. So I stole the code
> from OpenBSD.
> 
>  > get 12,800 keypresses in a second, though.  The only other
>  > problem that I see is that I remember ofwcons taking up a lot of
>  > CPU when the polling cycle is increased.  This was several years
>  > ago, though, so it might be different now.  Have you compared
>  > CPU usage with your patch?
>  > 
> top says "0.5% sys" when I use OFW_POLL_HZ with 100. But when I
> change the value to 20, top said "0.0% sys". With the value 20,
> I had no lost characters on console. So in practice, the OFW_POLL_HZ
> could be set to 20 or less than the value. 
> Thank you for pointing out.
> 

Look at rev 1.4 of ofw_console.c.  It looks like the polling interval
was changed from 50 to 4 in response to poor performance and a certain
lockup potential.  Your change to batch the console writes will
undoubtably help this, though.

It would be very intereting to get some testing results from a blade100
and an Ultra5/10 on this.  If people with this hardware can test and
report back both whether it helps/hurts and if it had any impact on CPU
load, I'll commit it.

Scott



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